We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster
galaxies, with r-band monochromatic luminosity Lr = 8 14L (4:3 7:5 1044 erg s 1). These
super spiral galaxies are also giant and massive, with diameter D = 57 134 kpc and stellar mass
Mstars = 0:3 3:4 1011M. We nd 53 super spirals out of a complete sample of 1616 SDSS
galaxies with redshift z < 0:3 and Lr > 8L. The closest example is found at z = 0:089. We use
existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS
and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the
extreme masses and rapid SFRs of 5 65M yr 1 place super spirals in a sparsely populated region
of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a
diverse range of environments, from isolation to cluster centers. We nd four super spiral galaxy
systems that are late-stage major mergers{a possible clue to their formation. We suggest that super
spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become
massive lenticular galaxies after they are cut o from their gas supply and their disks fade.
The completeness-corrected rate of stellar encounters with the Sun from the f...Sérgio Sacani
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial
velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which
come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds
to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...Sérgio Sacani
This document discusses observations of six lensed starburst galaxies at redshift ~2.5 using the Atacama Large Millimeter/submillimeter Array (ALMA). The key findings are:
1) ALMA detected emission and absorption lines of the CH+ molecule in the spectra of five out of the six galaxies, indicating dense shocks and highly turbulent reservoirs of cool gas extending over 10 kiloparsecs outside the starburst regions.
2) The broad CH+ emission lines trace shocks moving at ~40 km/s within dense gas, while the absorption lines reveal turbulent reservoirs with velocities of ~400 km/s.
3) The turbulent reservoirs have radii of 10-20 kilopar
This document summarizes a study that compiled a list of 220 spiral galaxies with quasars at their centers from the Sloan Digital Sky Survey Data Release 7. It analyzed the virial mass estimates of the quasars' supermassive black holes using three different calibration methods/datasets. Histograms of the black hole masses were created and showed a distribution ranging from 10^7 to 10^9 solar masses. Virial mass estimators relate the motion of gas around a black hole to its mass based on measured properties like emission line widths and luminosities.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
The stellar orbit distribution in present-day galaxies inferred from the CALI...Sérgio Sacani
Galaxy formation entails the hierarchical assembly of mass,
along with the condensation of baryons and the ensuing, selfregulating
star formation1,2
. The stars form a collisionless system
whose orbit distribution retains dynamical memory that
can constrain a galaxy’s formation history3
. The orbits dominated
by ordered rotation, with near-maximum circularity
λz≈ 1, are called kinematically cold, and the orbits dominated
by random motion, with low circularity λz≈ 0, are kinematically
hot. The fraction of stars on ‘cold’ orbits, compared with
the fraction on ‘hot’ orbits, speaks directly to the quiescence
or violence of the galaxies’ formation histories4,5
. Here we
present such orbit distributions, derived from stellar kinematic
maps through orbit-based modelling for a well-defined,
large sample of 300 nearby galaxies. The sample, drawn from
the CALIFA survey6, includes the main morphological galaxy
types and spans a total stellar mass range from 108.7 to 1011.9
solar masses. Our analysis derives the orbit-circularity distribution
as a function of galaxy mass and its volume-averaged
total distribution. We find that across most of the considered
mass range and across morphological types, there are more
stars on ‘warm’ orbits defined as 0.25 ≤λz≤ 0.8 than on either
‘cold’ or ‘hot’ orbits. This orbit-based ‘Hubble diagram’ provides
a benchmark for galaxy formation simulations in a cosmological
context.
Proper-motion age dating of the progeny of Nova Scorpii ad 1437Sérgio Sacani
‘Cataclysmic variables’ are binary star systems in which one
star of the pair is a white dwarf, and which often generate bright
and energetic stellar outbursts. Classical novae are one type of
outburst: when the white dwarf accretes enough matter from its
companion, the resulting hydrogen-rich atmospheric envelope
can host a runaway thermonuclear reaction that generates a rapid
brightening1–4. Achieving peak luminosities of up to one million
times that of the Sun5
, all classical novae are recurrent, on timescales
of months6
to millennia7
. During the century before and after an
eruption, the ‘novalike’ binary systems that give rise to classical
novae exhibit high rates of mass transfer to their white dwarfs8
.
Another type of outburst is the dwarf nova: these occur in binaries
that have stellar masses and periods indistinguishable from those
of novalikes9
but much lower mass-transfer rates10, when accretiondisk
instabilities11 drop matter onto the white dwarfs. The coexistence
at the same orbital period of novalike binaries and dwarf
novae—which are identical but for their widely varying accretion
rates—has been a longstanding puzzle9
. Here we report the recovery
of the binary star underlying the classical nova eruption of 11 March
ad 1437 (refs 12, 13), and independently confirm its age by propermotion
dating. We show that, almost 500 years after a classical-nova
event, the system exhibited dwarf-nova eruptions. The three other
oldest recovered classical novae14–16 display nova shells, but lack
firm post-eruption ages17,18, and are also dwarf novae at present.
We conclude that many old novae become dwarf novae for part of
the millennia between successive nova eruptions19,
Evidence for reflected_lightfrom_the_most_eccentric_exoplanet_knownSérgio Sacani
Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.22◦, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations may be caused by reflected light from the planet’s atmosphere and the dramatic change in star–planet separation surrounding the periastron passage.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
The completeness-corrected rate of stellar encounters with the Sun from the f...Sérgio Sacani
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial
velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which
come within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the
Oort cloud. 16 stars are found to come within 2 pc (although a few of these have dubious data). This is fewer than were found in a
similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars
with large radial velocity uncertainties (>10 km s−1
), and partly because of missing stars in GDR1 (especially at the bright end). The
closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometry predict
a much closer passage than pre-Gaia estimates, however: just 16 000 AU (90% confidence interval: 10 000–21 000 AU), which will
bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together
with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function
of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars
with implausibly large velocities), I estimate the rate of stellar encounters within 5 pc averaged over the past and future 5 Myr to be
545±59 Myr−1
. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds
to 87 ± 9 Myr−1 within 2 pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
Large turbulent reservoirs of cold molecular gas around high-redshift starbur...Sérgio Sacani
This document discusses observations of six lensed starburst galaxies at redshift ~2.5 using the Atacama Large Millimeter/submillimeter Array (ALMA). The key findings are:
1) ALMA detected emission and absorption lines of the CH+ molecule in the spectra of five out of the six galaxies, indicating dense shocks and highly turbulent reservoirs of cool gas extending over 10 kiloparsecs outside the starburst regions.
2) The broad CH+ emission lines trace shocks moving at ~40 km/s within dense gas, while the absorption lines reveal turbulent reservoirs with velocities of ~400 km/s.
3) The turbulent reservoirs have radii of 10-20 kilopar
This document summarizes a study that compiled a list of 220 spiral galaxies with quasars at their centers from the Sloan Digital Sky Survey Data Release 7. It analyzed the virial mass estimates of the quasars' supermassive black holes using three different calibration methods/datasets. Histograms of the black hole masses were created and showed a distribution ranging from 10^7 to 10^9 solar masses. Virial mass estimators relate the motion of gas around a black hole to its mass based on measured properties like emission line widths and luminosities.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
The stellar orbit distribution in present-day galaxies inferred from the CALI...Sérgio Sacani
Galaxy formation entails the hierarchical assembly of mass,
along with the condensation of baryons and the ensuing, selfregulating
star formation1,2
. The stars form a collisionless system
whose orbit distribution retains dynamical memory that
can constrain a galaxy’s formation history3
. The orbits dominated
by ordered rotation, with near-maximum circularity
λz≈ 1, are called kinematically cold, and the orbits dominated
by random motion, with low circularity λz≈ 0, are kinematically
hot. The fraction of stars on ‘cold’ orbits, compared with
the fraction on ‘hot’ orbits, speaks directly to the quiescence
or violence of the galaxies’ formation histories4,5
. Here we
present such orbit distributions, derived from stellar kinematic
maps through orbit-based modelling for a well-defined,
large sample of 300 nearby galaxies. The sample, drawn from
the CALIFA survey6, includes the main morphological galaxy
types and spans a total stellar mass range from 108.7 to 1011.9
solar masses. Our analysis derives the orbit-circularity distribution
as a function of galaxy mass and its volume-averaged
total distribution. We find that across most of the considered
mass range and across morphological types, there are more
stars on ‘warm’ orbits defined as 0.25 ≤λz≤ 0.8 than on either
‘cold’ or ‘hot’ orbits. This orbit-based ‘Hubble diagram’ provides
a benchmark for galaxy formation simulations in a cosmological
context.
Proper-motion age dating of the progeny of Nova Scorpii ad 1437Sérgio Sacani
‘Cataclysmic variables’ are binary star systems in which one
star of the pair is a white dwarf, and which often generate bright
and energetic stellar outbursts. Classical novae are one type of
outburst: when the white dwarf accretes enough matter from its
companion, the resulting hydrogen-rich atmospheric envelope
can host a runaway thermonuclear reaction that generates a rapid
brightening1–4. Achieving peak luminosities of up to one million
times that of the Sun5
, all classical novae are recurrent, on timescales
of months6
to millennia7
. During the century before and after an
eruption, the ‘novalike’ binary systems that give rise to classical
novae exhibit high rates of mass transfer to their white dwarfs8
.
Another type of outburst is the dwarf nova: these occur in binaries
that have stellar masses and periods indistinguishable from those
of novalikes9
but much lower mass-transfer rates10, when accretiondisk
instabilities11 drop matter onto the white dwarfs. The coexistence
at the same orbital period of novalike binaries and dwarf
novae—which are identical but for their widely varying accretion
rates—has been a longstanding puzzle9
. Here we report the recovery
of the binary star underlying the classical nova eruption of 11 March
ad 1437 (refs 12, 13), and independently confirm its age by propermotion
dating. We show that, almost 500 years after a classical-nova
event, the system exhibited dwarf-nova eruptions. The three other
oldest recovered classical novae14–16 display nova shells, but lack
firm post-eruption ages17,18, and are also dwarf novae at present.
We conclude that many old novae become dwarf novae for part of
the millennia between successive nova eruptions19,
Evidence for reflected_lightfrom_the_most_eccentric_exoplanet_knownSérgio Sacani
Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). We obtained CHIRON spectra to perform an independent estimation of the fundamental stellar parameters. New radial velocities from AAT and PARAS observations during periastron passage greatly improve our knowledge of the eccentric nature of the orbit. The combined analysis of our Keplerian orbital and Hipparcos astrometry show that the inclination of the planetary orbit is > 1.22◦, ruling out stellar masses for the companion. Our long-term robotic photometry show that the star is extremely stable over long timescales. Photometric monitoring of the star during predicted transit and periastron times using MOST rule out a transit of the planet and reveal evidence of phase variations during periastron. These possible photometric phase variations may be caused by reflected light from the planet’s atmosphere and the dramatic change in star–planet separation surrounding the periastron passage.
EXTINCTION AND THE DIMMING OF KIC 8462852Sérgio Sacani
To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star
over a wide wavelength range from the UV to the mid-infrared from October 2015 through December
2016, using Swift, Spitzer and at AstroLAB IRIS. The star faded in a manner similar to the longterm
fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period
reported is 22.1 ± 9.7 milli-mag yr−1
in the Swift wavebands, with amounts of 21.0 ± 4.5 mmag in
the groundbased B measurements, 14.0 ± 4.5 mmag in V , and 13.0 ± 4.5 in R, and a rate of 5.0 ± 1.2
mmag yr−1 averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at
& 3 σ by three different observatories operating from the UV to the IR. The presence of long-term
secular dimming means that previous SED models of the star based on photometric measurements
taken years apart may not be accurate. We find that stellar models with Tef f = 7000 - 7100 K and
AV ∼ 0.73 best fit the Swift data from UV to optical. These models also show no excess in the
near-simultaneous Spitzer photometry at 3.6 and 4.5 µm, although a longer wavelength excess from
a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of
the fading favors a relatively neutral color (i.e., RV & 5, but not flat across all the bands) compared
with the extinction law for the general ISM (RV = 3.1), suggesting that the dimming arises from
circumstellar material
We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part
of the Survey of H I in Extremely Low-Mass Dwarfs (SHIELD) project, which is a multi-wavelength
study of galaxies with H I masses in the range of 106-107:2 M discovered by the ALFALFA survey.
We have obtained spectra of the lone H II region in AGC 198691 with the new high-throughput
KPNO Ohio State Multi-Object Spectrograph (KOSMOS) on the Mayall 4-m as well as with the Blue
Channel spectrograph on the MMT 6.5-m telescope. These observations enable the measurement of the
temperature-sensitive [O III]4363 line and hence the determination of a \direct" oxygen abundance
for AGC 198691. We nd this system to be an extremely metal-decient (XMD) system with an
oxygen abundance of 12+log(O/H) = 7.02 0.03, making AGC 198691 the lowest-abundance starforming
galaxy known in the local universe. Two of the ve lowest-abundance galaxies known have
been discovered by the ALFALFA blind H I survey; this high yield of XMD galaxies represents a
paradigm shift in the search for extremely metal-poor galaxies.
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
We discovered two transient events in the Kepler eld with light curves that strongly suggest they
are type II-P supernovae. Using the fast cadence of the Kepler observations we precisely estimate
the rise time to maximum for KSN2011a and KSN2011d as 10.50:4 and 13.30:4 rest-frame days
respectively. Based on ts to idealized analytic models, we nd the progenitor radius of KSN2011a
(28020 R) to be signicantly smaller than that for KSN2011d (49020 R) but both have similar
explosion energies of 2.00:3 1051 erg.
The rising light curve of KSN2011d is an excellent match to that predicted by simple models of
exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models
predict possibly due to the supernova shockwave moving into pre-existing wind or mass-loss from the
RSG. A mass loss rate of 10 4 M yr 1 from the RSG can explain the fast rise without impacting
the optical
ux at maximum light or the shape of the post-maximum light curve.
No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar inter-
action suspected in the fast rising light curve. The early light curve of KSN2011d does show excess
emission consistent with model predictions of a shock breakout. This is the rst optical detection of
a shock breakout from a type II-P supernova.
TEMPORAL EVOLUTION OF THE HIGH-ENERGY IRRADIATION AND WATER CONTENT OF TRAPPI...Sérgio Sacani
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could
harbour liquid water on their surfaces. UV observations are essential to measure their high-energy
irradiation, and to search for photodissociated water escaping from their putative atmospheres. Our
new observations of TRAPPIST-1 Ly-α line during the transit of TRAPPIST-1c show an evolution of
the star emission over three months, preventing us from assessing the presence of an extended hydrogen
exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history
of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the
orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape.
However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped
once they entered the habitable zone. We caution that these estimates remain limited by the large
uncertainty on the planet masses. They likely represent upper limits on the actual water loss because
our assumptions maximize the XUV-driven escape, while photodissociation in the upper atmospheres
should be the limiting process. Late-stage outgassing could also have contributed significant amounts
of water for the outer, more massive planets after they entered the habitable zone. While our results
suggest that the outer planets are the best candidates to search for water with the JWST, they also
highlight the need for theoretical studies and complementary observations in all wavelength domains
to determine the nature of the TRAPPIST-1 planets, and their potential habitability.
Keywords: planetary systems - Stars: individual: TRAPPIST-1
Periodic mass extinctions_and_the_planet_x_model_reconsideredSérgio Sacani
The 27 Myr periodicity in the fossil extinction record has been con-
firmed in modern data bases dating back 500 Myr, which is twice the time
interval of the original analysis from thirty years ago. The surprising regularity
of this period has been used to reject the Nemesis model. A second
model based on the sun’s vertical galactic oscillations has been challenged
on the basis of an inconsistency in period and phasing. The third astronomical
model originally proposed to explain the periodicity is the Planet
X model in which the period is associated with the perihelion precession
of the inclined orbit of a trans-Neptunian planet. Recently, and unrelated
to mass extinctions, a trans-Neptunian super-Earth planet has been proposed
to explain the observation that the inner Oort cloud objects Sedna
and 2012VP113 have perihelia that lie near the ecliptic plane. In this
Letter we reconsider the Planet X model in light of the confluence of the
modern palaeontological and outer solar system dynamical evidence.
Key Words: astrobiology - planets and satellites - Kuiper belt:
general - comets: general
Probing the innermost_regions_of_agn_jets_and_their_magnetic_fields_with_radi...Sérgio Sacani
Desde 1974, observações feitas com o chamado Long Baseline Interferometry, ou VLBI, combinaram sinais de um objeto cósmico recebidos em diferentes rádio telescópios espalhados pelo globo para criar uma antena com o tamanho equivalente à maior separação entre elas. Isso fez com que fosse possível fazer imagens com uma nitidez sem precedentes, com uma resolução 1000 vezes melhor do que Hubble consegue na luz visível. Agora, uma equipe internacional de astrônomos quebrou todos os recordes combinando 15 rádio telescópios na Terra e a antena de rádio da missão RadioAstron, da agência espacial russa, na órbita da Terra. O trabalho, liderado pelo Instituto de Astrofísica de Andalucía, o IAA-CSIC, forneceu novas ideias sobre a natureza das galáxias ativas, onde um buraco negro extremamente massivo engole a matéria ao redor enquanto simultaneamente emite um par de jatos de partículas de alta energia e campos magnéticos a velocidades próximas da velocidade da luz.
Observações feitas no comprimento de onda das micro-ondas são essenciais para explorar esses jatos, já que os elétrons de alta energia se movendo em campos magnéticos são mais proficientes em produzir micro-ondas. Mas a maioria das galáxias ativas com jatos brilhantes estão a bilhões de anos-luz de distância da Terra, de modo que esses jatos são minúsculos no céu. Desse modo a alta resolução é essencial para observar esses jatos em ação e então revelar fenômenos como as ondas de choque e a turbulência que controla o quanto de luz é produzida num dado tempo. “Combinando pela primeira vez rádio telescópios na Terra com rádio telescópios no espaço, operando na máxima resolução, tem permitido que a nossa equipe crie uma antena que tem um tamanho equivalente a 8 vezes o diâmetro da Terra, correspondendo a 20 micro arcos de segundo”, disse José L; Gómez, o líder da equipe no Instituto de Astrofísica de Andalucía, IAA-CSIC.
Evidence for the_thermal_sunyaev-zeldovich_effect_associated_with_quasar_feed...Sérgio Sacani
Using a radio-quiet subsample of the Sloan Digital Sky Survey spectroscopic quasar
catalogue, spanning redshifts 0.5–3.5, we derive the mean millimetre and far-infrared
quasar spectral energy distributions (SEDs) via a stacking analysis of Atacama Cosmology
Telescope and Herschel-Spectral and Photometric Imaging REceiver data. We
constrain the form of the far-infrared emission and find 3σ–4σ evidence for the thermal
Sunyaev-Zel’dovich (SZ) effect, characteristic of a hot ionized gas component with
thermal energy (6.2 ± 1.7) × 1060 erg. This amount of thermal energy is greater than
expected assuming only hot gas in virial equilibrium with the dark matter haloes of
(1 − 5) × 1012h
−1M that these systems are expected to occupy, though the highest
quasar mass estimates found in the literature could explain a large fraction of this
energy. Our measurements are consistent with quasars depositing up to (14.5±3.3) τ
−1
8
per cent of their radiative energy into their circumgalactic environment if their typical
period of quasar activity is τ8 × 108 yr. For high quasar host masses, ∼ 1013h
−1M,
this percentage will be reduced. Furthermore, the uncertainty on this percentage is
only statistical and additional systematic uncertainties enter at the 40 per cent level.
The SEDs are dust dominated in all bands and we consider various models for dust
emission. While sufficiently complex dust models can obviate the SZ effect, the SZ
interpretation remains favoured at the 3σ–4σ level for most models.
First identification of_direct_collapse_black_holes_candidates_in_the_early_u...Sérgio Sacani
The first black hole seeds, formed when the Universe was younger than ⇠ 500Myr, are recognized
to play an important role for the growth of early (z ⇠ 7) super-massive black holes.
While progresses have been made in understanding their formation and growth, their observational
signatures remain largely unexplored. As a result, no detection of such sources has been
confirmed so far. Supported by numerical simulations, we present a novel photometric method
to identify black hole seed candidates in deep multi-wavelength surveys.We predict that these
highly-obscured sources are characterized by a steep spectrum in the infrared (1.6−4.5μm),
i.e. by very red colors. The method selects the only 2 objects with a robust X-ray detection
found in the CANDELS/GOODS-S survey with a photometric redshift z & 6. Fitting their
infrared spectra only with a stellar component would require unrealistic star formation rates
(& 2000M# yr−1). To date, the selected objects represent the most promising black hole seed
candidates, possibly formed via the direct collapse black hole scenario, with predicted mass
> 105M#. While this result is based on the best photometric observations of high-z sources
available to date, additional progress is expected from spectroscopic and deeper X-ray data.
Upcoming observatories, like the JWST, will greatly expand the scope of this work.
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...Sérgio Sacani
This document summarizes the results of a study analyzing the total mass density profiles of 14 early-type galaxies using two-dimensional stellar kinematic data out to large radii of 2-6 half-light radii. The study finds that the total density profiles are well described by a nearly-isothermal power law with density proportional to radius from 0.1 to at least 4 half-light radii. The average logarithmic slope is -2.19 with a small scatter of only 0.11. This places tight constraints on galaxy formation models and illustrates the power of extended two-dimensional stellar kinematic observations.
WHERE IS THE FLUX GOING? THE LONG-TERM PHOTOMETRIC VARIABILITY OF BOYAJIAN’S ...Sérgio Sacani
We present ∼ 800 days of photometric monitoring of Boyajian’s Star (KIC 8462852) from the AllSky
Automated Survey for Supernovae (ASAS-SN) and ∼ 4000 days of monitoring from the All Sky
Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian’s Star
has steadily decreased at a rate of 6.3 ± 1.4 mmag yr−1
, such that the star is now 1.5% fainter than it
was in February 2015. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian’s
Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a
monotonic decline. We analyze a sample of ∼ 1000 comparison stars of similar brightness located in
the same ASAS-SN field and demonstrate that the recent fading is significant at & 99.4% confidence.
The 2015 − 2017 dimming rate is consistent with that measured with Kepler data for the time period
from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models
for the star’s behavior proposed to date
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
T he effect_of_orbital_configuration)_on_the_possible_climates_and_habitabili...Sérgio Sacani
This research article explores how the orbital configuration of Kepler-62f, a potentially habitable exoplanet in a five-planet system, could affect its climate and habitability. N-body simulations were used to determine the stable range of orbital eccentricities for Kepler-62f. Climate simulations using two global climate models then examined the planet's surface habitability across this range of eccentricities and for different atmospheric compositions. The simulations found multiple combinations of orbital and atmospheric parameters that could allow for surface liquid water on Kepler-62f, including higher orbital eccentricities coupled with high planetary obliquity or atmospheric CO2 levels above 3 bars.
Young remmants of_type_ia_supernovae_and_their_progenitors_a_study_of_snr_g19_03Sérgio Sacani
Type Ia supernovae, with their remarkably homogeneous light curves and spectra, have been used as
standardizable candles to measure the accelerating expansion of the Universe. Yet, their progenitors
remain elusive. Common explanations invoke a degenerate star (white dwarf) which explodes upon
reaching close to the Chandrasekhar limit, by either steadily accreting mass from a companion star
or violently merging with another degenerate star. We show that circumstellar interaction in young
Galactic supernova remnants can be used to distinguish between these single and double degenerate
progenitor scenarios. Here we propose a new diagnostic, the Surface Brightness Index, which can
be computed from theory and compared with Chandra and VLA observations. We use this method
to demonstrate that a double degenerate progenitor can explain the decades-long
ux rise and size
increase of the youngest known Galactic SNR G1.9+0.3. We disfavor a single degenerate scenario.
We attribute the observed properties to the interaction between a steep ejecta prole and a constant
density environment. We suggest using the upgraded VLA to detect circumstellar interaction in
the remnants of historical Type Ia supernovae in the Local Group of galaxies. This may settle the
long-standing debate over their progenitors.
Subject headings: ISM: supernova remnants | radio continuum: general | X-rays: general | bi-
naries: general | circumstellar matter | supernovae: general | ISM: individual
objects(SNR G1.9+0.3)
Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of
1011.5 K. Relativistic boosting can increase its observed value, but apparent brightness temperatures
much in excess of 1013 K are inaccessible using ground-based very long baseline interferometry (VLBI)
at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission
RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as
small as 26 µas (2.7 light months) and brightness temperature in excess of 1013 K. These measurements
challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive
black holes and require a much higher Doppler factor than what is determined from jet apparent
kinematics.
Keywords: galaxies: active — galaxies: jets — radio continuum: galaxies — techniques: interferometric
— quasars: individual (3C 273)
Uma grande equipe de astrônomos registrou uma supernova extremamente luminosa numa galáxia massiva a cerca de 3.82 bilhões de anos-luz de distância.
A explosão recém-descoberta, denominada de ASASSN-15Ih, pertence à classe mais luminosa de supernovas, chamada de supernovas superluminosas.
"Ela parece ter originado numa grande galáxia, em contraste com a maioria das supernovas superluminosas, que normalmente se originam em galáxias anãs com formação de estrelas", disse o Dr. Subo Dong, do Kavli Institute for Astronomy and Astrophysics e coautor do artigo publicado na revista Science que descreve a descoberta.
"Nós estimamos o raio efetivo para a galáxia de 7830 anos-luz e uma massa estelar de 200 bilhões de massas solares".
Também conhecida como SN 2015L, a ASASSN-15lh é aproximadamente 200 vezes mais poderosa do que uma típica explosão de supernova do Tipo Ia, cerca de 570 bilhões de vezes mais brilhante do que o nosso Sol, e vinte vezes mais brilhante do que todas as estrelas na nossa galáxia combinadas.
A 2 4_determination_of_the_local_value_of_the_hubble_constantSérgio Sacani
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to
reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%.
The bulk of this improvement comes from new, near-infrared observations of Cepheid
variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling
the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these
in turn leverage the magnitude-redshift relation based on 300 SNe Ia at z <0.15. All
19 hosts as well as the megamaser system NGC4258 have been observed with WFC3
in the optical and near-infrared, thus nullifying cross-instrument zeropoint errors in the
relative distance estimates from Cepheids. Other noteworthy improvements include a
33% reduction in the systematic uncertainty in the maser distance to NGC4258, a larger
sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to
the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of
Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW)
Cepheids.
Detection of lyman_alpha_emission_from_a_triply_imaged_z_6_85_galaxy_behind_m...Sérgio Sacani
We report the detection of Ly emission at 9538A
in the Keck/DEIMOS and HST WFC3
G102 grism data from a triply-imaged galaxy at z = 6:846 0:001 behind galaxy cluster MACS
J2129.4 0741. Combining the emission line wavelength with broadband photometry, line ratio upper
limits, and lens modeling, we rule out the scenario that this emission line is [O II] at z = 1:57. After
accounting for magnication, we calculate the weighted average of the intrinsic Ly luminosity to be
1:31042 erg s 1 and Ly equivalent width to be 7415A. Its intrinsic UV absolute magnitude at
1600A
is 18:60:2 mag and stellar mass (1:50:3)107 M, making it one of the faintest (intrinsic
LUV 0:14 L
UV) galaxies with Ly detection at z 7 to date. Its stellar mass is in the typical range
for the galaxies thought to dominate the reionization photon budget at z & 7; the inferred Ly escape
fraction is high (& 10%), which could be common for sub-L z & 7 galaxies with Ly emission. This
galaxy oers a glimpse of the galaxy population that is thought to drive reionization, and it shows
that gravitational lensing is an important avenue to probe the sub-L galaxy population.
Is there an_exoplanet_in_the_solar_systemSérgio Sacani
We investigate the prospects for the capture of the proposed Planet 9 from other
stars in the Sun’s birth cluster. Any capture scenario must satisfy three conditions:
the encounter must be more distant than ∼ 150 au to avoid perturbing the Kuiper
belt; the other star must have a wide-orbit planet (a & 100 au); the planet must be
captured onto an appropriate orbit to sculpt the orbital distribution of wide-orbit
Solar System bodies. Here we use N-body simulations to show that these criteria may
be simultaneously satisfied. In a few percent of slow close encounters in a cluster,
bodies are captured onto heliocentric, Planet 9-like orbits. During the ∼ 100 Myr
cluster phase, many stars are likely to host planets on highly-eccentric orbits with
apastron distances beyond 100 au if Neptune-sized planets are common and susceptible
to planet–planet scattering. While the existence of Planet 9 remains unproven, we
consider capture from one of the Sun’s young brethren a plausible route to explain such
an object’s orbit. Capture appears to predict a large population of Trans-Neptunian
Objects (TNOs) whose orbits are aligned with the captured planet, and we propose
that different formation mechanisms will be distinguishable based on their imprint on
the distribution of TNOs
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
This document analyzes the gamma-ray signal from the central Milky Way that is consistent with emission from annihilating dark matter particles. The authors re-examine Fermi data using cuts on an event parameter to improve gamma-ray maps and more easily separate components. They find the GeV excess is robust and well-fit by a 36-51 GeV dark matter particle annihilating to bottom quarks with a cross section of 1-3×10−26 cm3/s. The signal extends over 10 degrees from the Galactic Center and is spherically symmetric, disfavoring explanations from millisecond pulsars or gas interactions.
The canarias einstein_ring_a_newly_discovered_optical_einstein_ringSérgio Sacani
This document reports the discovery of a newly discovered optical Einstein ring (ER) called the "Canarias Einstein Ring". It was discovered serendipitously in imaging data from the Dark Energy Camera. Follow-up spectroscopy with the Gran Telescopio CANARIAS confirmed the nature of the system, with the lens being an early-type galaxy at a redshift of z=0.581 and the source being a starburst galaxy at z=1.165. Analysis of the system determined the Einstein radius to be 2.16 arcseconds and the total enclosed mass producing the lensing effect to be 1.86 ± 0.23 × 1012 solar masses.
The document contains multiple choice questions about various aspects of computer programming and C++. Specifically, it covers topics like components of the CPU, high-level vs low-level languages, functions, operators, data types, variable names, and processing of a C++ program from coding to execution.
[…] Ahora bien; JIMÉNEZ URE, como buen enamorado de la sabiduría, deja evidencias de una remarcada voz cartesiana: «[…] Pero, no soy testigo porque no experimenté el instante de mi creación o fecundación» (Cfr., p. 31). Aquí captamos dos secuencias del Empirismo Metodológico: la experiencia y la fecundación, contrastadas con un término («creación») teológico que deja entrever las raíces cristianas del autor […](Ramón E. Azócar A.)
We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part
of the Survey of H I in Extremely Low-Mass Dwarfs (SHIELD) project, which is a multi-wavelength
study of galaxies with H I masses in the range of 106-107:2 M discovered by the ALFALFA survey.
We have obtained spectra of the lone H II region in AGC 198691 with the new high-throughput
KPNO Ohio State Multi-Object Spectrograph (KOSMOS) on the Mayall 4-m as well as with the Blue
Channel spectrograph on the MMT 6.5-m telescope. These observations enable the measurement of the
temperature-sensitive [O III]4363 line and hence the determination of a \direct" oxygen abundance
for AGC 198691. We nd this system to be an extremely metal-decient (XMD) system with an
oxygen abundance of 12+log(O/H) = 7.02 0.03, making AGC 198691 the lowest-abundance starforming
galaxy known in the local universe. Two of the ve lowest-abundance galaxies known have
been discovered by the ALFALFA blind H I survey; this high yield of XMD galaxies represents a
paradigm shift in the search for extremely metal-poor galaxies.
A nearby yoiung_m_dwarf_with_wide_possibly_planetary_m_ass_companionSérgio Sacani
This document summarizes the identification of two young objects, TYC 9486-927-1 and 2MASS J21265040−8140293, as a likely very wide binary system. It presents revised astrometry showing they have common proper motion. Spectroscopy of the secondary yields a radial velocity consistent with the primary. Analysis of lithium absorption and kinematics suggests an age range of 10-45 Myr, with the secondary having an estimated mass in the planetary mass regime. If confirmed, this would be the widest known exoplanet system at over 4500 AU separation.
We discovered two transient events in the Kepler eld with light curves that strongly suggest they
are type II-P supernovae. Using the fast cadence of the Kepler observations we precisely estimate
the rise time to maximum for KSN2011a and KSN2011d as 10.50:4 and 13.30:4 rest-frame days
respectively. Based on ts to idealized analytic models, we nd the progenitor radius of KSN2011a
(28020 R) to be signicantly smaller than that for KSN2011d (49020 R) but both have similar
explosion energies of 2.00:3 1051 erg.
The rising light curve of KSN2011d is an excellent match to that predicted by simple models of
exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models
predict possibly due to the supernova shockwave moving into pre-existing wind or mass-loss from the
RSG. A mass loss rate of 10 4 M yr 1 from the RSG can explain the fast rise without impacting
the optical
ux at maximum light or the shape of the post-maximum light curve.
No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar inter-
action suspected in the fast rising light curve. The early light curve of KSN2011d does show excess
emission consistent with model predictions of a shock breakout. This is the rst optical detection of
a shock breakout from a type II-P supernova.
TEMPORAL EVOLUTION OF THE HIGH-ENERGY IRRADIATION AND WATER CONTENT OF TRAPPI...Sérgio Sacani
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could
harbour liquid water on their surfaces. UV observations are essential to measure their high-energy
irradiation, and to search for photodissociated water escaping from their putative atmospheres. Our
new observations of TRAPPIST-1 Ly-α line during the transit of TRAPPIST-1c show an evolution of
the star emission over three months, preventing us from assessing the presence of an extended hydrogen
exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history
of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the
orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape.
However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped
once they entered the habitable zone. We caution that these estimates remain limited by the large
uncertainty on the planet masses. They likely represent upper limits on the actual water loss because
our assumptions maximize the XUV-driven escape, while photodissociation in the upper atmospheres
should be the limiting process. Late-stage outgassing could also have contributed significant amounts
of water for the outer, more massive planets after they entered the habitable zone. While our results
suggest that the outer planets are the best candidates to search for water with the JWST, they also
highlight the need for theoretical studies and complementary observations in all wavelength domains
to determine the nature of the TRAPPIST-1 planets, and their potential habitability.
Keywords: planetary systems - Stars: individual: TRAPPIST-1
Periodic mass extinctions_and_the_planet_x_model_reconsideredSérgio Sacani
The 27 Myr periodicity in the fossil extinction record has been con-
firmed in modern data bases dating back 500 Myr, which is twice the time
interval of the original analysis from thirty years ago. The surprising regularity
of this period has been used to reject the Nemesis model. A second
model based on the sun’s vertical galactic oscillations has been challenged
on the basis of an inconsistency in period and phasing. The third astronomical
model originally proposed to explain the periodicity is the Planet
X model in which the period is associated with the perihelion precession
of the inclined orbit of a trans-Neptunian planet. Recently, and unrelated
to mass extinctions, a trans-Neptunian super-Earth planet has been proposed
to explain the observation that the inner Oort cloud objects Sedna
and 2012VP113 have perihelia that lie near the ecliptic plane. In this
Letter we reconsider the Planet X model in light of the confluence of the
modern palaeontological and outer solar system dynamical evidence.
Key Words: astrobiology - planets and satellites - Kuiper belt:
general - comets: general
Probing the innermost_regions_of_agn_jets_and_their_magnetic_fields_with_radi...Sérgio Sacani
Desde 1974, observações feitas com o chamado Long Baseline Interferometry, ou VLBI, combinaram sinais de um objeto cósmico recebidos em diferentes rádio telescópios espalhados pelo globo para criar uma antena com o tamanho equivalente à maior separação entre elas. Isso fez com que fosse possível fazer imagens com uma nitidez sem precedentes, com uma resolução 1000 vezes melhor do que Hubble consegue na luz visível. Agora, uma equipe internacional de astrônomos quebrou todos os recordes combinando 15 rádio telescópios na Terra e a antena de rádio da missão RadioAstron, da agência espacial russa, na órbita da Terra. O trabalho, liderado pelo Instituto de Astrofísica de Andalucía, o IAA-CSIC, forneceu novas ideias sobre a natureza das galáxias ativas, onde um buraco negro extremamente massivo engole a matéria ao redor enquanto simultaneamente emite um par de jatos de partículas de alta energia e campos magnéticos a velocidades próximas da velocidade da luz.
Observações feitas no comprimento de onda das micro-ondas são essenciais para explorar esses jatos, já que os elétrons de alta energia se movendo em campos magnéticos são mais proficientes em produzir micro-ondas. Mas a maioria das galáxias ativas com jatos brilhantes estão a bilhões de anos-luz de distância da Terra, de modo que esses jatos são minúsculos no céu. Desse modo a alta resolução é essencial para observar esses jatos em ação e então revelar fenômenos como as ondas de choque e a turbulência que controla o quanto de luz é produzida num dado tempo. “Combinando pela primeira vez rádio telescópios na Terra com rádio telescópios no espaço, operando na máxima resolução, tem permitido que a nossa equipe crie uma antena que tem um tamanho equivalente a 8 vezes o diâmetro da Terra, correspondendo a 20 micro arcos de segundo”, disse José L; Gómez, o líder da equipe no Instituto de Astrofísica de Andalucía, IAA-CSIC.
Evidence for the_thermal_sunyaev-zeldovich_effect_associated_with_quasar_feed...Sérgio Sacani
Using a radio-quiet subsample of the Sloan Digital Sky Survey spectroscopic quasar
catalogue, spanning redshifts 0.5–3.5, we derive the mean millimetre and far-infrared
quasar spectral energy distributions (SEDs) via a stacking analysis of Atacama Cosmology
Telescope and Herschel-Spectral and Photometric Imaging REceiver data. We
constrain the form of the far-infrared emission and find 3σ–4σ evidence for the thermal
Sunyaev-Zel’dovich (SZ) effect, characteristic of a hot ionized gas component with
thermal energy (6.2 ± 1.7) × 1060 erg. This amount of thermal energy is greater than
expected assuming only hot gas in virial equilibrium with the dark matter haloes of
(1 − 5) × 1012h
−1M that these systems are expected to occupy, though the highest
quasar mass estimates found in the literature could explain a large fraction of this
energy. Our measurements are consistent with quasars depositing up to (14.5±3.3) τ
−1
8
per cent of their radiative energy into their circumgalactic environment if their typical
period of quasar activity is τ8 × 108 yr. For high quasar host masses, ∼ 1013h
−1M,
this percentage will be reduced. Furthermore, the uncertainty on this percentage is
only statistical and additional systematic uncertainties enter at the 40 per cent level.
The SEDs are dust dominated in all bands and we consider various models for dust
emission. While sufficiently complex dust models can obviate the SZ effect, the SZ
interpretation remains favoured at the 3σ–4σ level for most models.
First identification of_direct_collapse_black_holes_candidates_in_the_early_u...Sérgio Sacani
The first black hole seeds, formed when the Universe was younger than ⇠ 500Myr, are recognized
to play an important role for the growth of early (z ⇠ 7) super-massive black holes.
While progresses have been made in understanding their formation and growth, their observational
signatures remain largely unexplored. As a result, no detection of such sources has been
confirmed so far. Supported by numerical simulations, we present a novel photometric method
to identify black hole seed candidates in deep multi-wavelength surveys.We predict that these
highly-obscured sources are characterized by a steep spectrum in the infrared (1.6−4.5μm),
i.e. by very red colors. The method selects the only 2 objects with a robust X-ray detection
found in the CANDELS/GOODS-S survey with a photometric redshift z & 6. Fitting their
infrared spectra only with a stellar component would require unrealistic star formation rates
(& 2000M# yr−1). To date, the selected objects represent the most promising black hole seed
candidates, possibly formed via the direct collapse black hole scenario, with predicted mass
> 105M#. While this result is based on the best photometric observations of high-z sources
available to date, additional progress is expected from spectroscopic and deeper X-ray data.
Upcoming observatories, like the JWST, will greatly expand the scope of this work.
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...Sérgio Sacani
This document summarizes the results of a study analyzing the total mass density profiles of 14 early-type galaxies using two-dimensional stellar kinematic data out to large radii of 2-6 half-light radii. The study finds that the total density profiles are well described by a nearly-isothermal power law with density proportional to radius from 0.1 to at least 4 half-light radii. The average logarithmic slope is -2.19 with a small scatter of only 0.11. This places tight constraints on galaxy formation models and illustrates the power of extended two-dimensional stellar kinematic observations.
WHERE IS THE FLUX GOING? THE LONG-TERM PHOTOMETRIC VARIABILITY OF BOYAJIAN’S ...Sérgio Sacani
We present ∼ 800 days of photometric monitoring of Boyajian’s Star (KIC 8462852) from the AllSky
Automated Survey for Supernovae (ASAS-SN) and ∼ 4000 days of monitoring from the All Sky
Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian’s Star
has steadily decreased at a rate of 6.3 ± 1.4 mmag yr−1
, such that the star is now 1.5% fainter than it
was in February 2015. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian’s
Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a
monotonic decline. We analyze a sample of ∼ 1000 comparison stars of similar brightness located in
the same ASAS-SN field and demonstrate that the recent fading is significant at & 99.4% confidence.
The 2015 − 2017 dimming rate is consistent with that measured with Kepler data for the time period
from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models
for the star’s behavior proposed to date
This document summarizes a blind HI survey of the southern Milky Way zone of avoidance conducted with the Parkes radio telescope. The survey detected 883 galaxies at Galactic longitudes 212° < l < 36° and latitudes |b| < 5° to a sensitivity of 6 mJy per 27 km/s channel. Fifty-one percent of detections had known optical/near-infrared counterparts, while 27% had new counterparts identified. The survey delineated large-scale structures in the Puppis and Great Attractor regions for the first time. Several newly identified galaxy concentrations and clusters were revealed that help trace the Great Attractor Wall.
T he effect_of_orbital_configuration)_on_the_possible_climates_and_habitabili...Sérgio Sacani
This research article explores how the orbital configuration of Kepler-62f, a potentially habitable exoplanet in a five-planet system, could affect its climate and habitability. N-body simulations were used to determine the stable range of orbital eccentricities for Kepler-62f. Climate simulations using two global climate models then examined the planet's surface habitability across this range of eccentricities and for different atmospheric compositions. The simulations found multiple combinations of orbital and atmospheric parameters that could allow for surface liquid water on Kepler-62f, including higher orbital eccentricities coupled with high planetary obliquity or atmospheric CO2 levels above 3 bars.
Young remmants of_type_ia_supernovae_and_their_progenitors_a_study_of_snr_g19_03Sérgio Sacani
Type Ia supernovae, with their remarkably homogeneous light curves and spectra, have been used as
standardizable candles to measure the accelerating expansion of the Universe. Yet, their progenitors
remain elusive. Common explanations invoke a degenerate star (white dwarf) which explodes upon
reaching close to the Chandrasekhar limit, by either steadily accreting mass from a companion star
or violently merging with another degenerate star. We show that circumstellar interaction in young
Galactic supernova remnants can be used to distinguish between these single and double degenerate
progenitor scenarios. Here we propose a new diagnostic, the Surface Brightness Index, which can
be computed from theory and compared with Chandra and VLA observations. We use this method
to demonstrate that a double degenerate progenitor can explain the decades-long
ux rise and size
increase of the youngest known Galactic SNR G1.9+0.3. We disfavor a single degenerate scenario.
We attribute the observed properties to the interaction between a steep ejecta prole and a constant
density environment. We suggest using the upgraded VLA to detect circumstellar interaction in
the remnants of historical Type Ia supernovae in the Local Group of galaxies. This may settle the
long-standing debate over their progenitors.
Subject headings: ISM: supernova remnants | radio continuum: general | X-rays: general | bi-
naries: general | circumstellar matter | supernovae: general | ISM: individual
objects(SNR G1.9+0.3)
Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of
1011.5 K. Relativistic boosting can increase its observed value, but apparent brightness temperatures
much in excess of 1013 K are inaccessible using ground-based very long baseline interferometry (VLBI)
at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission
RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as
small as 26 µas (2.7 light months) and brightness temperature in excess of 1013 K. These measurements
challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive
black holes and require a much higher Doppler factor than what is determined from jet apparent
kinematics.
Keywords: galaxies: active — galaxies: jets — radio continuum: galaxies — techniques: interferometric
— quasars: individual (3C 273)
Uma grande equipe de astrônomos registrou uma supernova extremamente luminosa numa galáxia massiva a cerca de 3.82 bilhões de anos-luz de distância.
A explosão recém-descoberta, denominada de ASASSN-15Ih, pertence à classe mais luminosa de supernovas, chamada de supernovas superluminosas.
"Ela parece ter originado numa grande galáxia, em contraste com a maioria das supernovas superluminosas, que normalmente se originam em galáxias anãs com formação de estrelas", disse o Dr. Subo Dong, do Kavli Institute for Astronomy and Astrophysics e coautor do artigo publicado na revista Science que descreve a descoberta.
"Nós estimamos o raio efetivo para a galáxia de 7830 anos-luz e uma massa estelar de 200 bilhões de massas solares".
Também conhecida como SN 2015L, a ASASSN-15lh é aproximadamente 200 vezes mais poderosa do que uma típica explosão de supernova do Tipo Ia, cerca de 570 bilhões de vezes mais brilhante do que o nosso Sol, e vinte vezes mais brilhante do que todas as estrelas na nossa galáxia combinadas.
A 2 4_determination_of_the_local_value_of_the_hubble_constantSérgio Sacani
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to
reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%.
The bulk of this improvement comes from new, near-infrared observations of Cepheid
variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling
the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these
in turn leverage the magnitude-redshift relation based on 300 SNe Ia at z <0.15. All
19 hosts as well as the megamaser system NGC4258 have been observed with WFC3
in the optical and near-infrared, thus nullifying cross-instrument zeropoint errors in the
relative distance estimates from Cepheids. Other noteworthy improvements include a
33% reduction in the systematic uncertainty in the maser distance to NGC4258, a larger
sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to
the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of
Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW)
Cepheids.
Detection of lyman_alpha_emission_from_a_triply_imaged_z_6_85_galaxy_behind_m...Sérgio Sacani
We report the detection of Ly emission at 9538A
in the Keck/DEIMOS and HST WFC3
G102 grism data from a triply-imaged galaxy at z = 6:846 0:001 behind galaxy cluster MACS
J2129.4 0741. Combining the emission line wavelength with broadband photometry, line ratio upper
limits, and lens modeling, we rule out the scenario that this emission line is [O II] at z = 1:57. After
accounting for magnication, we calculate the weighted average of the intrinsic Ly luminosity to be
1:31042 erg s 1 and Ly equivalent width to be 7415A. Its intrinsic UV absolute magnitude at
1600A
is 18:60:2 mag and stellar mass (1:50:3)107 M, making it one of the faintest (intrinsic
LUV 0:14 L
UV) galaxies with Ly detection at z 7 to date. Its stellar mass is in the typical range
for the galaxies thought to dominate the reionization photon budget at z & 7; the inferred Ly escape
fraction is high (& 10%), which could be common for sub-L z & 7 galaxies with Ly emission. This
galaxy oers a glimpse of the galaxy population that is thought to drive reionization, and it shows
that gravitational lensing is an important avenue to probe the sub-L galaxy population.
Is there an_exoplanet_in_the_solar_systemSérgio Sacani
We investigate the prospects for the capture of the proposed Planet 9 from other
stars in the Sun’s birth cluster. Any capture scenario must satisfy three conditions:
the encounter must be more distant than ∼ 150 au to avoid perturbing the Kuiper
belt; the other star must have a wide-orbit planet (a & 100 au); the planet must be
captured onto an appropriate orbit to sculpt the orbital distribution of wide-orbit
Solar System bodies. Here we use N-body simulations to show that these criteria may
be simultaneously satisfied. In a few percent of slow close encounters in a cluster,
bodies are captured onto heliocentric, Planet 9-like orbits. During the ∼ 100 Myr
cluster phase, many stars are likely to host planets on highly-eccentric orbits with
apastron distances beyond 100 au if Neptune-sized planets are common and susceptible
to planet–planet scattering. While the existence of Planet 9 remains unproven, we
consider capture from one of the Sun’s young brethren a plausible route to explain such
an object’s orbit. Capture appears to predict a large population of Trans-Neptunian
Objects (TNOs) whose orbits are aligned with the captured planet, and we propose
that different formation mechanisms will be distinguishable based on their imprint on
the distribution of TNOs
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
This document analyzes the gamma-ray signal from the central Milky Way that is consistent with emission from annihilating dark matter particles. The authors re-examine Fermi data using cuts on an event parameter to improve gamma-ray maps and more easily separate components. They find the GeV excess is robust and well-fit by a 36-51 GeV dark matter particle annihilating to bottom quarks with a cross section of 1-3×10−26 cm3/s. The signal extends over 10 degrees from the Galactic Center and is spherically symmetric, disfavoring explanations from millisecond pulsars or gas interactions.
The canarias einstein_ring_a_newly_discovered_optical_einstein_ringSérgio Sacani
This document reports the discovery of a newly discovered optical Einstein ring (ER) called the "Canarias Einstein Ring". It was discovered serendipitously in imaging data from the Dark Energy Camera. Follow-up spectroscopy with the Gran Telescopio CANARIAS confirmed the nature of the system, with the lens being an early-type galaxy at a redshift of z=0.581 and the source being a starburst galaxy at z=1.165. Analysis of the system determined the Einstein radius to be 2.16 arcseconds and the total enclosed mass producing the lensing effect to be 1.86 ± 0.23 × 1012 solar masses.
The document contains multiple choice questions about various aspects of computer programming and C++. Specifically, it covers topics like components of the CPU, high-level vs low-level languages, functions, operators, data types, variable names, and processing of a C++ program from coding to execution.
[…] Ahora bien; JIMÉNEZ URE, como buen enamorado de la sabiduría, deja evidencias de una remarcada voz cartesiana: «[…] Pero, no soy testigo porque no experimenté el instante de mi creación o fecundación» (Cfr., p. 31). Aquí captamos dos secuencias del Empirismo Metodológico: la experiencia y la fecundación, contrastadas con un término («creación») teológico que deja entrever las raíces cristianas del autor […](Ramón E. Azócar A.)
El documento discute por qué se recomienda tomar leche después de una intoxicación. Explica que la leche puede actuar como un tampón para contrarrestar sustancias cáusticas suaves debido a su pH ligeramente ácido. También puede diluir el tóxico de la misma manera que el agua. Sin embargo, no se recomienda la leche para todas las intoxicaciones, solo en casos de ingesta de cáusticos suaves. La composición de la leche también puede formar una barrera temporal en la mucosa gástrica o inactivar algunos tóxicos
Las Cortes de Cádiz se convocaron en 1810 como una asamblea constituyente para gobernar España durante la invasión francesa. Estaban compuestas principalmente por burgueses liberales y promulgaron la Constitución de 1812, que estableció los principios de soberanía nacional, igualdad de derechos y monarquía constitucional. La constitución también otorgó derechos individuales a los ciudadanos y estableció un estado unitario y confesional.
Premio Nonspot 2011 Central Lechera AsturianaLeticia Grafiá
El documento presenta una propuesta de campaña de marketing para la marca Central Lechera Asturiana. La campaña se centra en Carmen, una mujer de 45 años que trabaja fuera y dentro de casa, y tiene como objetivo fidelizar a los clientes actuales e incentivar la compra de nuevos clientes. La campaña consiste en tres fases que incluyen promociones, eventos, publicidad en televisión, radio y vallas publicitarias para atraer a Carmen y su familia.
El documento compara la novela Alicia en el País de las Maravillas de Lewis Carroll con la película The Matrix de los hermanos Wachowski, encontrando similitudes entre los personajes y escenas. Identifica a Alicia y Neo como protagonistas que descubren un nuevo mundo, y compara a Morfeo con el Conejo Blanco que guían a los protagonistas. También compara a la Reina de Corazones con el Oráculo y el Constructor, y analiza las similitudes entre otros personajes y escenas de ambas obras.
Este documento describe las diferentes fuerzas y el concepto de equilibrio. Explica que un cuerpo está en equilibrio cuando la fuerza neta sobre él es cero y su aceleración es cero. Describe dos tipos de fuerzas: fuerzas de contacto que requieren contacto físico y fuerzas de campo que actúan a distancia. Luego menciona ejemplos de fuerzas fundamentales como la gravitatoria y electromagnética, y la fuerza de rozamiento que se opone al movimiento y depende de la naturaleza de las superficies y de la fuer
Este documento discute dos árboles en el Paraíso según el Génesis: el Árbol de la Vida y el Árbol del Conocimiento del Bien y del Mal. También explora conceptos como el Camino del Árbol de la Vida, la Cabala, los Sefirot y los Senderos como etapas de la conciencia y la creación. Finalmente, ofrece un análisis astrológico-alquímico y un informe personalizado basado en el árbol de la vida.
Mar tiene una reunión con unos clientes en su primer día como nueva comercial de una imprenta. Sin embargo, la reunión no sale bien y Mar desordena la oficina de los clientes. Más tarde, los clientes llaman quejándose y el jefe de Mar le advierte que debe pensar antes de actuar para no perder clientes importantes. Mar se enfada y abandona su puesto de trabajo.
Prezentace Michala Janíka o tom, jak navýšit tržby e-shopu před Vánoci 2016 s pomocí Mergada. Prezentaci Michal představil na ShopCommu 2016 v Bratislavě. Podrobnosti najdete v článku na www.mergado.cz/shopcomm-2016-bratislava-prezentace
This document is a dissertation by Joakim Carlsen submitted in 2014/2015 for a Bsc(Honours) in Applied Physics. It investigates detecting massive galaxies at high redshift (z > 4) using photometric data from the Dark Energy Survey (DES). The dissertation aims to identify massive galaxy candidates at z > 4 based on their colors and fit their spectral energy distributions using photometric redshift modeling software. Several high redshift massive galaxy candidates were identified and their properties were analyzed, with the most promising candidates to be proposed for follow-up spectroscopy to confirm their redshifts.
Off nuclear star_formation_and_obscured_activity_in_the_luminous_infrared_gal...Sérgio Sacani
The document summarizes observations of the luminous infrared galaxy NGC 2623 from multiple telescopes. Hubble Space Telescope images reveal over 100 bright star clusters in a 3.2 kpc extension south of the galaxy's nucleus, making it one of the richest concentrations of clusters observed. The clusters have ages between 1-100 Myr based on their optical colors. Archival GALEX data show the extension is very bright in far-ultraviolet but less significant at longer wavelengths. Spitzer data detect [Ne V] emission, confirming the presence of an active galactic nucleus. The off-nuclear star formation corresponds to a rate of 0.1-0.2 solar masses per year, while the bulk of the infrared
A giant ring_like_structure_at_078_z_086_displayed_by_gr_bsSérgio Sacani
This document describes the discovery of a giant ring-like structure in the observable universe displayed by 9 gamma ray bursts (GRBs) between redshifts of 0.78 and 0.86. The ring has a diameter of 1720 Mpc, over five times larger than the expected transition scale to homogeneity. The ring lies at a distance of 2770 Mpc with major and minor diameters of 43° and 30°, respectively. The probability of this structure occurring by random chance is calculated to be 2 × 10-6. This ring-shaped feature contradicts the cosmological principle of large-scale homogeneity and isotropy, and the physical mechanism responsible is unknown.
A spectroscopic sample_of_massive_galaxiesSérgio Sacani
This document describes a study of 16 massive galaxies at z ~ 2 selected from the 3D-HST spectroscopic survey based on the detection of a strong 4000 Angstrom break in their spectra. Spectroscopy and imaging from HST/WFC3 are used to determine accurate redshifts, stellar population properties, and structural parameters. The sample significantly increases the number of spectroscopically confirmed evolved galaxies at z ~ 2 with robust size measurements. The analysis populates the mass-size relation and finds it is consistent with local relations but with smaller sizes by a factor of 2-3. A model is presented where the observed size evolution is explained by quenching of increasingly larger star-forming galaxies at a rate set by
This document summarizes evidence that submillimeter galaxies (SMGs) at redshift 3-6 may be progenitors of compact quiescent galaxies observed at redshift 2. It compares properties of a sample of z~2 quiescent galaxies with a statistical sample of z>3 SMGs in the COSMOS field. It finds that the formation redshifts of the z~2 galaxies match the observed redshift distribution of z>3 SMGs. It also finds that the space densities and properties such as sizes, stellar masses, and internal velocities of the two populations are consistent with an evolutionary connection, assuming SMG starbursts have a duty cycle of 42+40 Myr. This suggests SMGs may represent an early burst
Alma observations of_feed_and_feedback_in_nearby_seyfert_galaxiesSérgio Sacani
The ALMA observations of NGC 1433 reveal a nuclear gaseous spiral structure within the central kpc. This spiral winds up into a pseudo-ring at ~200 pc from the center. Near the nucleus, there is intense high-velocity CO emission up to 200 km/s that is interpreted as an outflow, involving 3.6 million solar masses of molecular gas and a flow rate of ~7 solar masses per year. The outflow could be driven by both the central star formation and AGN through its radio jets. Continuum emission at 0.87 mm is detected only at the very center and likely comes from thermal dust emission from the molecular torus expected in this Seyfert 2 galaxy.
Alma observations of_feeding_and_feedback_in_nearby_seyfert_galaxies_outflow_...Sérgio Sacani
ALMA observations of the Seyfert 2 galaxy NGC 1433 reveal a nuclear gaseous spiral structure within a nuclear ring encircling a nuclear stellar bar. Near the nucleus, there is intense high-velocity CO emission interpreted as an AGN-driven molecular outflow. The outflow involves a molecular mass of 3.6 million solar masses and a flow rate of about 7 solar masses per year. Continuum emission at the center is likely thermal dust emission from a molecular torus expected in this Seyfert 2 galaxy. The observations probe gas dynamics within 24 parsecs of the active galactic nucleus.
This pilot survey used modest aperture telescopes to image 8 nearby spiral galaxies in order to search for stellar tidal streams. Ultra-deep imaging revealed 6 previously undetected extensive (up to 30 kpc) stellar structures likely from tidally disrupted satellites. A diversity of tidal feature morphologies was found, including great circle-like streams, remote shells, and jets emerging from disks. Simulations predict tidal debris should be common and match the observed variety, providing evidence minor mergers have shaped disk galaxies since z=1.
The identification of_93_day_periodic_photometric_variability_for_yso_ylw_16aSérgio Sacani
This study identifies a 93 day periodic photometric variability in the Class I young stellar object (YSO) YLW 16A in the Rho Ophiuchus star forming region. Light curve analysis reveals variations of ~0.5 magnitudes in the Ks band over this period. The authors propose a triple system model consisting of an inner binary with a 93 day period eclipsed by a warped circumbinary disk, with a tertiary companion at ~40 AU responsible for warping the disk. This model is similar to one previously proposed for another YSO, WL 4, and may indicate such triple systems with eclipsing disks are common around young stars. Understanding these systems can provide insights into stellar and planetary formation and evolution.
This summarizes a scientific study on long-distance quantum teleportation between two laboratories separated by 55 meters but connected by 2 kilometers of fiber optic cable. The key points are:
1) Researchers teleported quantum states (qubits) carried by photons at 1.3 micrometer wavelengths onto photons at 1.55 micrometer wavelengths between the two laboratories.
2) The qubits were encoded in time-bin superpositions and entanglement rather than polarization to make them more robust against decoherence in optical fibers.
3) A partial Bell state measurement was performed using linear optics at the receiving end to probabilistically teleport the quantum states over the long distance.
The most luminous_galaxies_discovered_by_wiseSérgio Sacani
This document presents a sample of 20 extremely luminous galaxies discovered by the Wide-field Infrared Survey Explorer (WISE). Five of these galaxies have infrared luminosities exceeding 1014 solar luminosities, the highest infrared luminosity threshold yet observed. They were selected using criteria requiring weak or no detection in the first two WISE bands but strong detections in the third and fourth bands. Spectral energy distribution modeling suggests their high luminosities are powered by obscured active galactic nuclei with hot dust temperatures around 450 Kelvin. The existence of such luminous galaxies at redshifts above 3 provides constraints on the early growth of supermassive black holes through rapid accretion.
A higher efficiency_of_converting_gas_to_stars_push_galaxies_at_z_1_6_well_ab...Sérgio Sacani
Galáxias formando estrelas em taxas extremas a nove bilhões de anos atrás eram mais eficientes do que a média das galáxias atuais, descobriram os pesquisadores.
A maioria das estrelas acredita-se localizam-se na sequência principal onde quanto maior a massa da galáxia, mais eficiente ela é na formação de novas estrelas. Contudo, de vez em quando uma galáxia apresentará uma explosão de novas estrelas que brilham mais do que o resto. Uma colisão entre duas grandes galáxias é normalmente a causa dessas fases de explosões de formação de estrelas, onde o gás frio que reside nas grandes nuvens moleculares torna-se o combustível para sustentar essas altas taxas de formação de estrelas.
A questão que os astrônomos têm feito é se essas explosões de estrelas no início o universo foram o resultado de se ter um suprimento de gás abundante, ou se as galáxias convertiam o gás de maneira mais eficiente.
Um novo estudo, publicado no Astrophysical Journal Letters de 15 de Outubro, liderado por John Silverman, do Kavli Institute for Physics and Mathematics of the Universe, estudou o conteúdo do gás monóxido de carbono (CO) em sete galáxias de explosão de estrelas muito distantes, quando o universo tinha apenas 4 bilhões de anos de vida. Isso foi possível devido a capacidade do Atacama Large Millimiter/Submillimiter Array (ALMA), localizado no platô no topo da montanha no Chile, que trabalha para detectar as ondas eletromagnéticas no comprimento de onda milimétrico (importante para se estudar o gás molecular) e um nível de sensibilidade que só agora começa a ser explorado pelos astrônomos.
Os pesquisadores descobriram que a quantidade de gás CO emitido já tinha diminuído, mesmo apesar da galáxia continuar a formar estrelas em altas taxas. Essas observações são similares àquelas registradas para as galáxias de explosões de estrelas próximas da Terra atualmente, mas a quantidade da depleção de gás não foi tão rápida quanto se esperava. Isso levou os pesquisadores a concluírem que poderia haver um contínuo aumento na eficiência, dependendo em de quanto acima da taxa de se formar estrelas ela está da sequência principal.
The green valley_is_a_red_herring_galaxy_zoo_reveals_two_evolutionary_pathwaysSérgio Sacani
This document summarizes research using data from Galaxy Zoo, SDSS, and GALEX to study how star formation is quenched in low-redshift galaxies. The key findings are:
1) Taking galaxy morphology into account, the "green valley" is not a single transitional state, as was previously thought.
2) Only a small population of blue early-type galaxies rapidly transition across the green valley as their morphology transforms from disk to spheroid and star formation is quenched quickly.
3) The majority of blue star-forming galaxies have significant disks and retain their late-type morphology as their star formation rates decline very slowly.
4) Different evolutionary pathways are observed for early- and late-type
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
The exceptional soft_x_ray_halo_of_the_galaxy_merger_ngc6240Sérgio Sacani
The document summarizes a recent 150-ks Chandra observation of the galaxy merger NGC 6240. Extended soft X-ray emission is detected over a 110x80 kpc region around NGC 6240. Spectral analysis finds the emission comes from hot gas with a temperature of around 7.5 million K and a total mass of about 10^10 solar masses. The gas properties suggest widespread star formation over the past 200 Myr rather than a recent nuclear starburst. The fate of the diffuse hot gas after the galaxy merger is uncertain but it may be retained and evolve into the halo of an elliptical galaxy.
Lenz et al. discovered that soft particles at the nano- and microscale can form "clumpy crystals" where particles partially overlap and form regular lattices of clumps. This challenges ideas that soft materials will behave similarly to atomic and molecular systems. The discovery provides another example of how soft materials display unconventional behavior. An analysis of the satellites orbiting Andromeda found that about half are rotating coherently in a thin planar structure, providing a new constraint on galaxy formation theories. Further evidence suggests organized planar distributions of satellites may be common for nearby galaxy groups. The findings compound issues with the number of predicted versus observed satellites and suggest the structures themselves are not ancient.
The document presents observations of the starburst galaxy NGC 253 using near-infrared imaging and spectroscopy as well as mid-infrared spectroscopy. The observations are used to derive physical properties of the starburst such as the star formation rate, stellar population, and evolutionary stage. Evolutionary synthesis modeling is applied to interpret the observations and show that the starburst in NGC 253 is in a late phase, has been ongoing for 20-30 million years, and is consistent with a modified Salpeter initial mass function.
The physical conditions_in_a_pre_super_star_cluster_molecular_cloud_in_the_an...Sérgio Sacani
The document summarizes a study of an extreme molecular cloud in the Antennae galaxies that has properties consistent with forming a globular cluster. ALMA observations reveal a cloud with a radius of 24 pc and mass greater than 5 million solar masses. While capable of forming a globular cluster, a lack of associated thermal radio emission indicates star formation has not yet begun to alter the environment, suggesting the cloud is in an early stage of evolution. For the cloud to be confined as observed, an external pressure over 10,000 times greater than typical interstellar pressure is required, supporting the theory that high pressures are needed to form globular clusters in extreme environments like mergers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
1. Draft version January 8, 2016
Preprint typeset using LATEX style emulateapj v. 5/2/11
SUPERLUMINOUS SPIRAL GALAXIES
Patrick M. Ogle1
, Lauranne Lanz1
, Cyril Nader1,2
, George Helou1
1IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 and
2University of California, Los Angeles
Draft version January 8, 2016
ABSTRACT
We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster
galaxies, with r-band monochromatic luminosity Lr = 8 − 14L∗
(4.3 − 7.5 × 1044
erg s−1
). These
super spiral galaxies are also giant and massive, with diameter D = 57 − 134 kpc and stellar mass
Mstars = 0.3 − 3.4 × 1011
M . We find 53 super spirals out of a complete sample of 1616 SDSS
galaxies with redshift z < 0.3 and Lr > 8L∗
. The closest example is found at z = 0.089. We use
existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS
and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the
extreme masses and rapid SFRs of 5 − 65M yr−1
place super spirals in a sparsely populated region
of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a
diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy
systems that are late-stage major mergers–a possible clue to their formation. We suggest that super
spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become
massive lenticular galaxies after they are cut off from their gas supply and their disks fade.
1. INTRODUCTION
The most massive galaxies in the universe are thought
to form from the largest density peaks in the primordial
matter distribution. Galaxy mergers change the initial
galaxy mass function, forming more massive galaxies by
combining less massive ones. The result is the galaxy
mass distribution we see in the local universe, empirically
described by the Schechter (1976) luminosity function,
together with a morphology-dependent mass-to-light ra-
tio. The luminosity function also depends upon the star
formation history of galaxies, regulated by gas content,
gas accretion, stellar feedback, and active galactic nu-
cleus (AGN) feedback. Galaxy mergers play an impor-
tant role here too, since tidal torques in merging systems
force gas into the galaxy centers, leading to starburst ac-
tivity that grows the stellar bulge and AGN activity that
grows the supermassive black hole (Toomre & Toomre
1972; Barnes & Hernquist 1991; Hopkins et al. 2009).
Galaxies segregate into two major classes based on
color and morphology (Strateva et al. 2001; Lintott et
al. 2008). Blue, star-forming disks (late-type galaxies,
LTGs) lie in one region of color-space called the blue-
sequence. Red-and-dead spheroids (early-type galaxies,
ETGs) lie in a different region of color space called the
red sequence. LTGs demonstrate a correlation between
star formation rate (SFR) and stellar mass (Mstars) called
the star-forming main sequence (SFMS: Brinchmann et
al. 2004; Elbaz et al. 2007; Wuyts et al. 2011). The
SFMS may be a consequence of an equilibrium between
inflowing gas and star-formation driven outflows, with
the specific star formation rate (SSFR) regulated by the
halo mass growth rate (Lilly et al. 2013). Most ETGs
on the other hand have much lower SFRs because they
lack the cold gas needed to sustain star formation.
It appears that there is a limit to the mass of star-
forming disk galaxies of roughly 3 × 1010
M , with the
ogle@ipac.caltech.edu
most massive disk galaxies transitioning away from the
main sequence as their SSFR declines. This decline ap-
pears to be a gradual process, occurring over a period
longer than 1 Gyr after the gas supply to the galaxy disk
has been interrupted (Schawinski et al. 2014). Rapid
quenching does not appear to occur for most galaxies
that remain disk galaxies, contrary to early attempts
to explain the apparently bimodal distribution of galaxy
colors.
A number of mechanisms have been suggested to ex-
plain why the gas supply is interrupted for the most
massive disk galaxies. Major galaxy mergers may dis-
rupt merging disk galaxies and transform them rapidly
into elliptical galaxies (Baldry et al. 2004), though this
does not explain the transformation of galaxies that re-
main disks. The accretion of cold gas onto a galaxy
may be stopped when the galaxy halo becomes massive
enough that accretion shocks develop, interrupting the
cold streams of gas needed to replenish the disk (Dekel
& Birnboim 2006). Increasing AGN feedback from a
growing supermassive black hole may shock or eject gas
from the galaxy disk, reducing its capacity to form stars
(Hopkins et al. 2006; Ogle, Lanz, & Appleton 2014).
Ram-pressure stripping of the interstellar medium (ISM)
by the intercluster medium (ICM) of a galaxy cluster can
also remove cold gas (Sivanandam, Rieke, & Rieke 2014).
Studying the most massive spiral galaxies can give us
clues as to which of the above evolutionary processes
are primarily responsible for converting star-forming
disk galaxies into red-and-dead lenticulars or ellipticals.
The existence of rapidly star-forming, massive spirals
with Mstars > 1011
M indicates that disk galaxies can
postpone this fate under special circumstances. We
present here the most optically luminous and biggest
spiral galaxies at redshift z < 0.3, found by mining the
NASA/IPAC Extragalactic Database (NED). We assume
a cosmology with H0 = 70, Ωm = 0.3, and ΩΛ = 0.7 for
computing all linear sizes and luminosities.
arXiv:1511.00659v2[astro-ph.GA]7Jan2016
2. 2 Ogle et al.
2. SAMPLE
This project is an offshoot of our work to determine
the completeness of NED and explore its potential for
systematic studies of galaxy populations (Ogle, P. et
al., in preparation). NED provides a unique fusion of
multi-wavelength photometry from Galaxy Evolution Ex-
plorer (GALEX), Sloan Digital Sky Survey (SDSS), and
the 2-Micron All-Sky Survey (2MASS), among others,
which we augment by Wide-field Infrared Survey Ex-
plorer (WISE) photometry, that allows us to estimate
stellar masses and SFRs. We compared the redshift dis-
tribution of galaxies in NED at z < 0.3 to a model
redshift distribution for the universe derived using a
redshift-independent luminosity function, in order to es-
timate the spectroscopic completeness of NED. We used
the Schechter (1976) luminosity function fits of Blanton
et al. (2003), which are based on ∼150,000 SDSS galax-
ies as our benchmark. We adopt their characteristic ab-
solute magnitude value of M∗
−5 log10 h = −20.44±0.01
(L∗
= 5.41×1043
erg s−1
at 6200˚A) for the SDSS r-band
luminosity function. The redshift limit was made large
enough to capture the rarest, most luminous galaxies,
but not so large as to require consideration of redshift
evolution in the luminosity function.
2.1. SDSS r-band Selection of the most Optically
Luminous Galaxies
SDSS is the largest source of spectroscopic redshifts,
with a spectroscopic selection limit of r = 17.77 (Strauss
et al. 2002). We find that NED is complete over the
SDSS footprint out to z = 0.3 for galaxies with Lr > 8L∗
,
the most optically luminous and massive galaxies in the
low-redshift universe. Our sample is chosen from the
797,729 galaxies (type=G) in NED with spectroscopic
redshifts z < 0.3, in the SDSS footprint, and detected
in SDSS r band. We apply Galactic extinction correc-
tions (tabulated by NED) and K-corrections to the r-
band magnitudes prior to making our sample selection.
We find 1616 galaxies with redshift z < 0.3 and luminos-
ity Lr > 8L∗
, which constitute our Ogle et al. Galaxy
Catalog (OGC). The most luminous galaxy in the OGC
is a 20L∗
elliptical brightest cluster galaxy (BCG).
2.2. UV Selection Method for Super Spiral Galaxies
We make a further selection for UV emission because
we are interested in finding the most massive, actively
star-forming disk galaxies. We recently matched and in-
tegrated the GALEX All-Sky Survey Catalog (GASC)
and GALEX Medium Sky Survey Catalog (GMSC) with
NED, using an automated, statistical algorithm (Ogle
et al. 2015). We inspected the SDSS images of all
196 galaxies from the OGC that are detected in the
GALEX NUV band (the OGC-UV subsample). Of these,
we find 46 NUV-detected, Lr > 8L∗
galaxies with spi-
ral morphology (Table 1). The remaining NUV sources
include 118 ellipticals, 11 galaxies with E+A spectra,
2 quasi-stellar objects (QSOs) with extended emission,
and 19 galaxies with erroneous redshifts or magnitudes.
The most luminous elliptical galaxy in OGC-UV is a
16L∗
BCG, while the most luminous spiral galaxy has
Lr = 14L∗
.
2.3. Morphological Selection Method for Super Spiral
Galaxies
We inspected the 310 brightest galaxies of the full OGC
sample, those with Lr > 10.5L∗
, to see if we are missing
any spirals with UV selection. Of these, we classified 11
super spirals, 253 ellipticals, 38 galaxies with erroneous
redshifts or magnitudes, 6 lenticulars, 1 irregular, and 1
E+A galaxy. This inventory includes 7 additional super
spirals (Table 1) that are not in the OGC-UV sample.
Of these, 4 have no GALEX sources nearby, and 3 oth-
ers have nearby GALEX sources that should be matched
in NED, but are not, possibly because of confusion. This
shows that our NUV selection, while relatively efficient
(47/196) compared to morphological selection (11/310),
leads to an incomplete sample, with only 4/11 super spi-
rals recovered in this luminosity range. Part of the in-
completeness (3/11) is owing to incomplete matching of
GALEX with NED, while the rest (4/11) may be at-
tributed to the GALEX detection limit or coverage.
3. PHOTOMETRY
We conduct our investigation of super spirals primar-
ily with photometry compiled by NED. We use SDSS
DR6 u, g, r, i, z photometry measured with the CModel
method, which combines exponential plus deVaucouleurs
model fitting. GALEX FUV and NUV photometry is
taken from the GASC and GMSC, measured within a
Kron elliptical aperture. We use 2MASS J, H, Ks to-
tal magnitudes from the 2MASS Extended Source Cat-
alog (2MASX). NED objects are matched to AllWISE
sources using the Gator tool in the Infrared Science
Archive (IRSA). We use AllWISE 4.6 and 12 µm pho-
tometry within the largest available fixed-radius aperture
of 24. 75, which is well-matched to the largest galaxy in
our sample, with semimajor axis a = 24. 5.
4. BASIC PROPERTIES OF SUPER SPIRALS
4.1. Optical and Mid-IR colors
The SDSS and WISE colors of super spirals lie along
the blue sequence, similarly to less luminous star-forming
disk galaxies (Figure 1(a)). The SDSS comparison sam-
ple is adopted from Alatalo et al. (2014), who show that
LTGs and ETGs classified by Galaxy Zoo (GZ) (Lintott
et al. 2008) are well-separated in WISE [4.6]−[12] vs.
SDSS u−r color space. The WISE [4.6]−[12] color ranges
from 2.0 to 4.2, typical of polycyclic aromatic hydrocar-
bon (PAH) and warm dust emission from gas-rich, ac-
tively star-forming galaxies. The u − r color ranges from
1.4 to 4.4, indicating star-forming disks with a range of
SSFR or dust extinction. We estimate differential K-
corrections of ∆(u − r) < 0.2 mag in the redshift range
z = 0.1−0.3, by convolving several spectral energy distri-
bution (SED) models (e.g., those in the Appendix) with
the SDSS filter curves. These corrections are not large
enough to explain the additional scatter in the observed
u − r colors of super spirals.
There is a shift in the locus of super spiral colors com-
pared to less-massive blue sequence galaxies. Super spi-
rals tend to have redder u − r and bluer [4.6]−[12] colors
compared to the SDSS distribution. This could in prin-
ciple indicate either lower SSFR or increased extinction.
However, the high SSFR of our sample (Figure 1(b)) runs
contrary to the first explanation. Six super spirals have
3. Super Spirals 3
Figure 1. (a) SDSS and WISE colors of super spirals (circles) compared to other SDSS galaxies classified as LTG or ETG by Lintott
et al. (2008). The infrared transition zone (IRTZ) is the mid-IR equivalent of the optical green valley (Alatalo et al. 2014). (b) Star
formation rates and stellar masses of super spirals compared to the SDSS-WISE sample of Chang et al. (2015). The dashed line indicates
the star-forming main sequence at z ∼ 0 (Elbaz et al. 2007). Galaxies above this line also have formation times that are generally less
than the age of the universe. Larger diamond symbols are for SDSS J094700.08+254045.7 (SS 16) and 2MASX J13275756+334529 (SS
05), with detailed SED analysis presented in the Appendix.
Figure 2. Super spirals range in diameter from 57 to 134 kpc. The
dashed and dotted-dashed lines indicate deprojected SFR surface
densities of 1 × 10−3 and 1 × 10−2M yr−1 kpc−2, respectively.
u − r > 3.0, a value not attained by less luminous SDSS
LTGs. The two reddest galaxies (SS 53 and SS 09) may
be misclassified peculiar elliptical galaxies with promi-
nent shells. CGCG 122-067 (SS 50) may be redder be-
cause of its double bulge. The other 4 are clearly spirals,
and require further investigation and custom photome-
try to determine the cause of their unusually red u − r
colors.
4.2. Stellar Mass and Star Formation Rate
We estimate stellar mass from 2MASS Ks luminosity
together with an SDSS u − r color-dependent mass-to-
Figure 3. The largest super spiral galaxy, with Lr = 12L∗ and
an isophotal diameter of 134 kpc, 2MASX J16394598+4609058 (SS
03, z = 0.24713). The SDSS image is 50.7 (197 kpc) on each side.
light ratio estimated using the prescription of Bell et al.
(2003), giving M/L = 0.75 − 1.34M /L . We apply
a small correction to the stellar masses to convert to a
Chabrier initial mass function (IMF). This yields stellar
masses that are consistent with more sophisticated SED
template fitting (Appendix). We find stellar masses in
the range Mstars = 0.3 − 3.4 × 1011
M .
We estimate the SFR from the WISE 12 µm lumi-
nosity using the prescription of Chang et al. (2015),
which was established by SED-fitting more than 630,000
SDSS galaxies with magphys (da Cunha, Charlot, &
4. 4 Ogle et al.
1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
17 18 19 20 21 22 23 24
25 26 27 28 29 30 31 32
33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48
49 50 51 52 53
Figure 4. SDSS images of super spirals, 40 on a side. Examples with peculiar morphology: (1) multi-arm spiral, (8) asymmetric 2-arm
spiral, (10) QSO host with tidal arm, (21) ring galaxy, (23) possible tidal arm, (33) asymmetric disk, (34) possible secondary bulge, (53)
partial arms or shells.
Elbaz 2008). While accurate for star-forming galaxies,
this method may overestimate the star-formation rate for
early type galaxies where dust may be heated by other
sources not directly related to star formation, or in the
presence of a luminous AGN. We further validate our
WISE single-band SFRs against magphys SED-fitting
for two representative super spirals (Appendix). The
WISE 12 µm monochromatic luminosities of super spirals
range from 0.3 − 3.5 × 1044
erg s−1
(0.8 − 9.8 × 1010
L ),
corresponding to SFRs of 5 − 65M yr−1
.
We compare our sample to the SDSS-WISE sample of
Chang et al. (2015), who estimated SFR and Mstars with
magphys. We find that most super spirals lie well above
an extrapolation of the star-forming main sequence to
higher mass (Figure 1(b)). This is a region of the SFR
vs. mass diagram that is very sparsely populated. The
vast majority of SDSS disk galaxies in this mass range
have significantly lower SFR and SSFR.
Our r-band luminosity plus NUV detection criteria
tend to select galaxies with high global star formation
rates. However, the SDSS spectra reveal a relatively old
bulge stellar population for most super spirals. We do
find an indication of starburst activity in the SDSS bulge
spectra of 3 super spirals (SS 05–see Appendix, SS 15,
and SS 44) with strong young stellar population contri-
butions and high-equivalent width Hα emission. These
three galaxies also have relatively blue SDSS u−r colors
and red WISE [4.6]−[12] colors, both indicative of a high
global SSFR.
4.3. Active Galactic Nuclei
The super spiral galaxies in our sample contain 3
Seyfert 1 nuclei and 2 QSOs with broad Balmer lines and
strong [O iii] in their SDSS spectra (Table 1). There
is also 1 Seyfert 2 nucleus with strong [O iii] but nar-
row Balmer lines. There is likely a dominant contri-
5. Super Spirals 5
Figure 5. Distributions of super spiral and Galaxy Zoo spiral disk-bulge decomposition parameters, as measured by Simard et al. (2011):
(a) Bulge to total (B/T) r-band luminosity fraction, (b) disk inclination distribution compared to the sin(i) expectation for randomly
oriented disks (black curve), (c) bulge ellipticity, and (d) disk exponential scale length.
bution from the QSO to the IR luminosity of 2MASX
J15430777+1937522 (SS 10), which has the greatest
WISE 12 µm luminosity of our sample (1.7 × 1045
erg
s−1
or 4.3 × 1011
L ). The two QSOs are also detected
at X-ray wavelengths by ROSAT. One additional galaxy
(2MASX J10095635+2611324 = SS 45) is detected in
X-rays, but has no obvious signature of an AGN in its
SDSS nuclear spectrum. There is so far no indication
of any extended X-ray emission associated with super
spirals, though none have been specifically targeted for
this. It will be important to make deep X-ray observa-
tions of super spirals to quantify any X-ray halo emission
in comparison to giant elliptical galaxies. Only two super
spirals are detected by the NVSS radio survey (2MASX
J14472834+5908314 = SS 47 and CGCG 122-067 = SS
50), but the resolution is insufficient to distinguish be-
tween radio emission from star formation activity or from
a radio jet. The presence of luminous AGNs in 11% of
super spirals indicates that they are continuing to grow
their supermassive black holes. It is imperative to mea-
sure the distribution of bulge and supermassive black
hole masses in our super spiral sample to see if they fol-
low the same relation as lower-mass spiral bulges.
4.4. Size, SFR Surface Density, and Morphology
The sizes of super spirals range from 57 to 134 kpc,
with a median size of 72 kpc, using the SDSS DR6 r-
band isophotal diameter at 25.0 mag arcsec−2
(Table 1
and Figure 2). Their deprojected SFR surface densi-
ties range from 1.5 × 10−3
to 2.0 × 10−2
M yr−1
kpc−2
.
A plot of SFR vs. diameter shows considerable scat-
ter (Figure 2). However, the five most rapidly star-
forming galaxies, with log(SFR) > 1.6, all have diam-
eters D < 70 kpc. The most MIR-luminous super spi-
ral (SDSS J094700.08+254045.7, see Appendix), also has
the largest deprojected SFR surface density. The largest
super spiral, 2MASX J16394598+4609058 (SS 03, Figure
3), has a diameter of 134 kpc and a relatively low SFR
6. 6 Ogle et al.
surface density of 2.0 × 10−3
M yr−1
kpc−2
.
Super spirals display a range of morphologies, from
flocculent to grand-design spiral patterns (Figure 4). At
least 9 super spirals have prominent stellar bars visible in
the SDSS images (Table 1: Notes). There are morpho-
logical peculiarities in several cases, including one-arm
spirals, multi-arm spirals, rings, and asymmetric spiral
structure (Figure 4 and Table 1). These types of fea-
tures may indicate past or ongoing galaxy mergers or
collisions.
4.5. Bulge-disk Decomposition
We make use of the bulge-disk decompositions of
Simard et al. (2011) to quantify the relative contri-
butions of the bulge and disk to the luminosity of super
spirals (Table 2). The galaxy g and r band SDSS im-
ages are jointly fit by a de Vaucouleurs profile for the
bulge (Sersic index nb = 4), plus an exponential disk.
We compare super spirals to a representative subsample
of 4686 spiral galaxies with z > 0.09 classified by Galaxy
Zoo (GZ, Figure 5), with bulge-disk decompositions also
by Simard et al. (2011). We find a much narrower dis-
tribution of r-band bulge to total luminosity (B/T) for
super spirals, with a median value of B/T = 0.17, and a
deficit of B/T values < 0.1. A Kolmogorov-Smirnoff (K-
S) test shows that the distributions differ significantly,
with a probability of only 0.0027 that super spirals are
drawn from the same population as GZ spirals. The lack
of super spirals with B/T < 0.1 may be consistent with
a past history of significant merger activity. The bulge
ellipticity distribution of super spirals is not significantly
different from that of GZ spirals (Figure 5(c)). We note
that since the profile fits do not include a bar component,
the ellipticities may be augmented by the presence of a
bar or double bulge.
The disk inclination distribution of super spirals also
differs significantly from that of GZ spirals, and from
the expected sin(i) dependence (Figure 5(b)). A K-S
test gives a probability of 0.001 that super spirals and
GZ spirals are drawn from the same inclination distri-
bution. Only 5 (9%) of super spirals have inclinations
of i > 60◦
, compared to the expectation of 50% for ran-
domly oriented disks. This indicates that we are missing
roughly 45% of the super spirals in our luminosity range,
possibly because of internal extinction at the NUV selec-
tion wavelength. The GZ spiral inclination distribution
also differs from the expectation for randomly oriented
disks, with an excess at inclinations > 60◦
that may re-
veal a bias for GZ to classify edge on disks as spirals or
to misclassify edge-on lenticulars as spirals.
The median disk exponential scale length of super spi-
rals is 12.2 kpc, 2.3 times as large as the 5.3 kpc median
for GZ spirals, confirming the giant disk sizes of super
spirals (Figure 5d). A K-S test gives a probability of
0.001 that super spirals and GZ spirals are drawn
from the same size distribution. The galaxy smoothness
parameter (Simard et al. 2009), which quantifies the
fractional residuals to the model fit inside two half-light
radii, is S2 = 0.02−0.24 in r band. The B/T and S2 pa-
rameters of bulge-disk decompositions have been used by
others to quantitatively select early-type galaxies, with
B/T > 0.35 and S2 < 0.075 as criteria (Simard et al.
2009). Several super spirals in our sample meet these cri-
teria, but we are nevertheless confident of the detection
of a significant spiral disk in most of these cases.
5. GALAXY MERGER CANDIDATES
We find four super spiral merger candidates with ap-
parent double stellar bulges or double nuclei (Figure 6).
The SDSS spectra only cover the dominant or central
bulge or nucleus of each system. Spectroscopy of the
secondary bulges or nuclei will be necessary to confirm
or rule out these merger candidates as true physical pairs
or multiples.
The merger candidate 2MASX J08542169+0449308
(SS 22) appears to be a nearly equal mass major spiral
pre-merger. The arms of both spirals are wound in the
same direction, and the disks appear to be overlapping
in the plane of the sky. The stretched out spiral arms
of both spiral galaxy components, together with an ap-
parent tidal arm at PA= 0◦
(measured counterclockwise
from North) suggest an ongoing tidal interaction.
The merger candidate 2MASX J16014061+2718161
(SS 37) is a BCG, surrounded by several other disk
galaxy companions (Figures 6 and 7). The host clus-
ter is identified as GMBCG J240.41924+27.30444, with
a photometric redshift of 0.193 (Table 3). There are clear
distortions to the spiral structures of both spiral galaxy
components that appear to be involved in this merger.
The merger candidate 2MASX J09334777+2114362
(SS 46) appears to be a double AGN system. The pri-
mary, central nucleus is identified as an SDSS QSO. The
secondary nucleus has similar flux and color to the pri-
mary nucleus, but it does not have an SDSS spectrum to
confirm that it is a true physical double AGN. The galaxy
disk has high surface brightness, suggestive of starburst
activity. Faint outer spiral arms are also suggestive of a
recent galaxy interaction.
The merger candidate and BCG CGCG 122-067 (SS
50) appears to be a late stage ∼ 2:1 major merger. The
double bulge is surrounded by a common inner disk. Two
giant spiral arms emerge from this central disk, one from
each bulge, making a complete circuit around the disk.
A large gap is seen between the arms at PA= 0◦
− 90◦
.
There are three other possible merging nuclei, including
a bright green point source at PA= 270◦
, that raise the
possibility that this is a five-component multiple merger
system. Such multiple mergers are reminiscent of the
elliptical nest galaxies that are sometimes found at the
centers of galaxy clusters.
6. ENVIRONMENT
We checked NED for known galaxy clusters and groups
within 1 of each super spiral (Table 3). Seven of the su-
per spirals are candidate BCGs, within 0.8 of a galaxy
cluster. Two are candidate brightest group galaxies
(BGGs), within 1 of a compact galaxy group. Most
of the clusters only have photometric redshifts and have
yet to be verified spectroscopically. However, the pho-
tometric redshifts are all within ∆z = 0.04 of the super
spiral spectroscopic redshift, which suggests a true phys-
ical association. The two associations of super spirals
with compact groups are only based on their small an-
gular separation, with no independent redshift available
for the groups.
We used NED’s Environment Tool to further explore
the environments of the super spiral BCG and BGG can-
didates. This tool performs a redshift-constrained cone
7. Super Spirals 7
Figure 6. SDSS images of super spiral merger candidates. (a) Possible collision in progress of two spirals. (b) Possible collision or merger
of two spirals, also a brightest cluster galaxy (see also Figure 7). (c) High-surface brightness disk with possible double AGN, with faint
outer arms. The nucleus at the center is classified as an SDSS QSO. The second bright point source and possible AGN, near the edge of
the disk, has a similar color to the primary AGN. (d) Possible late-stage major merger with two stellar bulges, with a striking grand spiral
design surrounding both nuclei. Three other point sources may mark additional merging components or nuclei, reminiscent of nest galaxies
commonly found at the centers of galaxy clusters. Each SDSS image is 48 on a side.
Figure 7. Super spiral merger candidate 2MASXJ16014061+2718161 (SS 37) is the brightest cluster galaxy of galaxy cluster GMBCG
J240.41924+27.30444. The SDSS image is 203 (572 kpc) on each side.
8. 8 Ogle et al.
Figure 8. Super spiral 2MASX J11535621+4923562 (SS 17: Lr = 9.5L∗, D = 90 kpc) appears to be the brightest member of a previously
unidentified galaxy cluster (OGC 0586 CLUSTER). Compare to the less-luminous cluster spiral galaxy SDSS J115407.96+492200.8 (Lr =
2.8L∗, D = 39 kpc) in the lower left corner. The SDSS image is 203 (579 kpc) on each side.
9. Super Spirals 9
search for galaxies and galaxy clusters within a sphere of
comoving radius 10 Mpc. Because of the high redshifts
of the super spirals, only the most luminous galaxies in
their neighborhoods will tend to have measured spec-
troscopic redshifts in NED. We tabulate the number of
galaxies (N1) with spectroscopic redshifts that are within
1 Mpc and 500 km s−1
, and the number (N10) within
10 projected Mpc and 5000 km s−1
. The MSPM 05544
galaxy cluster, which appears to host the super spiral
CGCG 122-067 (SS 50) has the largest number of clus-
ter members with spectroscopic redshifts in NED (302),
while the SDSSCGB 59704 galaxy group has the small-
est number (2). These numbers should be taken as lower
limits to the cluster membership, depending primarily on
the SDSS spectroscopic selection limit and redshift.
There are likely more clusters to be discovered in
the vicinity of super spirals. For example, a clear
overdensity of galaxies is seen to the SE of 2MASX
J11535621+4923562 (SS 17, Figure 8). We verify a con-
centration of 69 galaxies within 10 Mpc and 5000 km s−1
(Table 3: OGC 0586 CLUSTER), using NED’s Environ-
ment tool. We estimate the mean redshift of OGC 0586
CLUSTER to be z = 0.166187, from 12 galaxies with
spectroscopic redshifts that are within 5 projected Mpc
of SS 17.
7. DISCUSSION
While super spirals have similar structure to less lumi-
nous spiral galaxies, they are impressive in the vastness of
their scale. A sense of how truly enormous these galax-
ies are can be gained by comparison to other galaxies
in the same cluster (Figure 8: OGC 0586 CLUSTER).
The 2MASX J11535621+4923562 (SS 17) super spiral at
z = 0.16673, with a luminosity of Lr = 9.5L∗
and a di-
ameter of 90 kpc, can be compared to a more common,
less luminous spiral galaxy which has Lr = 2.8L∗
and
a diameter of 39 kpc (13. 7), at about the same redshift
(z = 0.16721).
7.1. Analogs
It is natural to ask whether any analogs to super spi-
rals have been found at lower redshift. One well-known
example of a giant spiral galaxy is Malin 1 (z = 0.083),
initially suggested to be a proto-disk galaxy because of
its massive H i disk (Bothun et al. 1987). While Malin 1
does have one of the largest stellar disks known, with an
exponential scale length of 70 kpc, its global r-band lumi-
nosity (Lr = 1.8L∗
) is not nearly great enough to make
it into the OGC catalog. Its disk has very low surface
brightness and is not readily visible in SDSS images. As
further points of comparison, we estimate a global stellar
mass of 1.2 × 1010
M and global SFR of 1.2M yr−1
,
which are both much lower than the range spanned by
super spirals.
Other giant spiral galaxies are found in the local uni-
verse, though they also have considerably lower lumi-
nosities than the super spirals in our sample. Roman-
ishin (1983) find 107 spiral galaxies in the Uppsala
General Catalog of Galaxies (UGC) at z < 0.05, with
cosmology-corrected B-band isophotal diameters (at 25.0
mag arcsec−2
) of D = 65 − 150 kpc, similar to super spi-
rals. The 39 giant UGC spirals with SDSS photometry
in NED have r-band luminosities of 0.2 − 4.6L∗
, stel-
lar masses of 6 × 108
to 4 × 1010
M yr−1
, and SFRs of
0.2 − 7.7M yr−1
. Because of their considerably lower
stellar masses, they cannot be faded super spirals, but
could be useful analogs for understanding giant disks.
One of the largest giant spiral galaxies, UGC 2885 has a
rotational velocity of 280 km s−1
at a radius of 60 kpc,
and has undergone fewer than 10 rotations at its outer
edge in the age of the universe (Rubin, Ford, & Thonnard
1980).
Super spirals may also be related to the cold sub-mm
galaxies (SMGs) discovered at redshift z = 0.4−1 (Chap-
man et al. 2002). The relatively cold (∼ 30 K) dust tem-
peratures of these SMGs may indicate starburst activity
in a disk rather than a spheroid. In comparison, the FIR
SED of super spiral 2MASX J13275756+3345291 (SS 05,
see Appendix) is fit by the sum of a cold dust component
with T = 21+0.9
−1.8 K, likely from the disk, and a warmer
dust component with temperature T = 50+5.0
−2.8 K, likely
from the starbursting bulge. GN20, one of the most lu-
minous sub-mm detected star bursting galaxies, shows
molecular gas and star formation distributed in a 10 kpc
scale disk at z = 4.05 (Carilli, C. L. et al. 2010). Deep
near to mid-IR imaging of SMGs at intermediate red-
shifts will be necessary to measure their sizes and stellar
masses and better determine their relationship to super
spirals.
7.2. Formation and Survival
We estimate an average super spiral number density of
∼ 60 Gpc−3
at z < 0.3, correcting for ∼ 45% incomplete-
ness at high disk inclination (§4.5). The space density of
super spirals is therefore only ∼ 6% of the space den-
sity of elliptical galaxies in the same r-band luminosity
range. Even the largest galaxy evolution simulations to
date, such as the Illustris simulation (Vogelsberger et al.
2014; Snyder et al. 2015), covering ∼ 1.0 × 10−3
Gpc3
,
are not big enough to manufacture a significant number
of super spirals. Therefore, no adequate prediction ex-
ists for the expected number of super spirals at z < 0.3,
nor are there simulations showing how these giant disk
galaxies might form.
Super spirals could be formed by gas-rich major spiral-
spiral mergers. Simulations that collide two gas-rich disk
galaxies are able to produce post-merger spiral galaxies,
albeit at smaller scale (Barnes 2002; Springel & Hern-
quist 2005; Robertson et al 2006; Hopkins et al. 2009).
While merging stellar disks are typically destroyed, the
gas in the outer disks may combine to reform an even
larger gas and stellar disk. Orbital geometry may also be
important, with misaligned or retrograde orbits leading
to more gas-rich final merger products. If the dynami-
cal timescales are longer and the merger-induced torques
are even weaker in the outer disks of super spiral merg-
ers, this may also be conducive to the preservation of
gas disks and reformation of stellar disks. Alternatively,
super spirals might be formed more gradually, from the
inside out by accretion of cold gas. This may require
a relatively low halo mass in order to avoid accretion
shocks, which might prevent the gas from settling onto
the outer disk Dekel & Birnboim (2006). It will be im-
portant to study the spatial distribution of both neutral
gas and star formation in super spirals to gain further
insight into how their disks are formed.
It appears that the super spirals in our sample have
10. 10 Ogle et al.
so far avoided the fate of the vast majority of the most
massive galaxies and continue to form stars in spite of
their extreme mass, bucking the trend of cosmic down-
sizing. There are several possible reasons for this success.
First, super spirals may be robust to mergers because of
their massive, dissipative gaseous disks. It appears that
several super spirals in our sample have survived recent
major mergers with their star-forming disks intact. Sec-
ond, the supermassive black holes in super spiral bulges
may not be large enough to provide enough feedback to
drive away the gas in the giant galaxy disk. Third, the
halo mass may not be large enough to cut off cold accre-
tion onto the disk via accretion shocks. Finally, a large
enough gas reservoir may have already settled into the
disk to fuel star formation for a long time into the fu-
ture. Observations across the electromagnetic spectrum
are called for to distinguish among these possibilities.
7.3. Connection to Quenched Disk Galaxies
Super spirals occupy a relatively empty corner of the
SFR vs. stellar mass diagram (Figure 1b). They lie
above an extrapolation of the star-forming main se-
quence, at the most extreme mass and SFR. We find
that most super spirals have SSFR > 0.08 Gyr−1
. They
are forming stars at a rate that would allow them to
build up their mass in less than the age of the universe.
This is unlike similarly massive, yet much more com-
mon disk galaxies (early type spirals and lenticulars) that
fall below the star-forming main sequence, in what we
shall call the disk quenching sequence (DQS: the disk
galaxy subset of the green valley population). The disk-
quenching sequence is discussed in the context of SSFR
and UV color evolution by Schawinski et al. (2014),
and in the context of IR color evolution by Alatalo et
al. (2014). Quenching disk galaxies are likely greatly
reduced in their ability to form stars because their sup-
ply of cold gas has been cut off (e.g. Dekel & Birnboim
2006).
The most densely populated ridge of the DQS is close
to the median stellar mass of our super spiral sample
(Mstars = 1.1 × 1011
M ). We suggest that the majority
of disk galaxies along this ridge were once super spirals.
At a minimum, galaxies of this mass must have attained
an average SFR> 7M yr−1
in order to have formed in
less than the age of the universe. This would put them
squarely in the SFR and SSFR range of super spirals.
A further implication is that their D = 60 − 130 kpc
diameter stellar disks must have faded dramatically. If
fossil giant disks are detected around massive lenticular
galaxies with deep imaging, it will provide strong evi-
dence for this hypothesis. In addition, deep H i and CO
observations may reveal if their cold gas reservoir has
been entirely depleted or reduced to a level that is not
conducive to star formation.
8. CONCLUSIONS
We report the discovery of a large sample of the most
optically luminous (Lr > 8L∗
), biggest, and most mas-
sive spiral galaxies in the universe, which we call super
spirals. These galaxies are very rare (∼ 60 Gpc−3
), but
are easily observed out to z = 0.3 because of their high
luminosities and gigantic sizes. Super spirals are forming
stars at 5 − 65M yr−1
, a rate greater than their mean
SFR over the age of the universe. Bulge-disk decompo-
sitions confirm the presence of giant stellar disks, with
a median exponential scale length of 12.2 kpc, 2.3 times
the median scale length of less luminous spirals at the
same redshift. The bulge-to-total optical luminosity dis-
tribution is also significantly different for super spirals,
showing a deficit of galaxies with B/T < 0.1, and a con-
centration of galaxies with B/T = 0.1 − 0.2. Roughly
11% of super spirals have Seyfert or QSO nuclei, sug-
gesting that they are still actively adding mass to their
supermassive black holes. We find evidence that several
super spirals are undergoing major mergers, but manage
to keep their star-forming disks intact, and avoid being
transformed in to red-and-dead elliptical galaxies. Some
super spirals are brightest cluster galaxies, while others
appear to be isolated in the field. We suggest that super
spirals may be the progenitors of red and dead lenticular
galaxies of similar mass.
This work was made possible by the NASA/IPAC Ex-
tragalactic Database and the NASA/ IPAC Infrared Sci-
ence Archive, which are both operated by the Jet Propul-
sion Laboratory, California Institute of Technology, un-
der contract with the National Aeronautics and Space
Administration. We thank Joe Mazzarella, Ben Chan,
Marion Schmitz, and the rest of the NED team for use-
ful discussions and their support of this work. This pub-
lication makes use of data from the Galaxy Evolution
Explorer, retrieved from the Mikulski Archive for Space
Telescopes (MAST). STScI is operated by the Associa-
tion of Universities for Research in Astronomy, Inc., un-
der NASA contract NAS5-26555. Support for MAST for
non-HST data is provided by the NASA Office of Space
Science via grant NNX09AF08G and by other grants and
contracts. Funding for the Sloan Digital Sky Survey IV
has been provided by the Alfred P. Sloan Foundation, the
U.S. Department of Energy Office of Science, and the
Participating Institutions. SDSS-IV acknowledges sup-
port and resources from the Center for High-Performance
Computing at the University of Utah. The SDSS web
site is www.sdss.org. This publication makes use of data
products from the Two Micron All Sky Survey, which is
a joint project of the University of Massachusetts and
the Infrared Processing and Analysis Center/California
Institute of Technology, funded by the National Aeronau-
tics and Space Administration and the National Science
Foundation. This publication makes use of data products
from the Wide-field Infrared Survey Explorer, which is a
joint project of the University of California, Los Angeles,
and the Jet Propulsion Laboratory/California Institute
of Technology, funded by the National Aeronautics and
Space Administration. This work is based in part on ob-
servations made with the Spitzer Space Telescope, which
is operated by the Jet Propulsion Laboratory, California
Institute of Technology under a contract with NASA. We
also make use of data from Herschel, an ESA space obser-
vatory with science instruments provided by European-
led Principal Investigator consortia and with important
participation from NASA. We thank Katey Alatalo for
providing the SDSS-WISE comparison data in Figure 1a,
which is adapted from Alatalo et al. (2014). We thank
Phil Hopkins and Ski Antonucci for insightful discussions
that contributed to the manuscript. Finally, we thank
11. Super Spirals 11
the anonymous referee for suggesting that we analyze
available bulge-disk decompositions by Simard et al.
(2009), strengthening our results.
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Table 3
Candidate Cluster and Group Membership
SS NED Name Redshift N1a N10b Cluster Name Type Redshift ztypec Sep( )
02 2MASX J10405643-0103584 0.250303 1 8 SDSS CE J160.241898-01.069106 GClstr 0.254019 EST 0.013
04 2MASX J10100707+3253295 0.289913 2 17 GMBCG J152.52936+32.89139 GClstr 0.319000 PHOT 0.001
09 2MASX J09094480+2226078 0.285386 1 9 GMBCG J137.43670+22.43538 GClstr 0.303000 PHOT 0.000
12 2MASX J09260805+2405242 0.222451 1 22 WHL J092608.1+240524 GClstr 0.178000 PHOT 0.000
13 2MASX J17340613+6029190 0.275807 1 2 SDSSCGB 59704 GGroup 0.276000d SPEC 0.450
17 2MASX J11535621+4923562 0.166892 3 69 OGC 0586 CLUSTER GClstr 0.166187 SPEC 0.000
35 2MASX J12005393+4800076 0.278617 1 13 GMBCG J180.22479+48.00211 GClstr 0.252000 PHOT 0.001
37 2MASX J16014061+2718161 0.164554 3 163 GMBCG J240.41924+27.30444 GClstr 0.193000 PHOT 0.000
43 2MASX J13475962+3227100 0.223113 1 13 SDSSCGB 16827 GGroup · · · d · · · 0.748
50 CGCG 122-067 0.089008 5 302 MSPM 05544 GClstr 0.089190 SPEC 0.001
a Number of galaxies within 1 Mpc and 500 km s−1.
b Number of galaxies within 10 Mpc and 5000 km s−1.
c Redshift type, from NED. EST–estimated, PHOT–photometric, and SPEC–spectroscopic.
d The association of the super spiral galaxy with the compact group is based only on proximity on the sky. The group redshift in NED
for SDSSCGB 59704 appears to be based only on the redshift of the super spiral. None of the other galaxies in SDSSCGB 16827 have
measured redshifts.
APPENDIX
CUSTOM PHOTOMETRY AND VALIDATION OF MSTARS AND SFR
In order to validate our stellar mass and SFR estimates, which are based on Ks, u, r, and WISE 12 µm photometry,
we make a more detailed analysis of two representative examples from our super spiral sample. We remeasure their
photometry in matched apertures, rather than relying on catalog photometry. Then we fit their SEDs to make full use of
the available multi-band photometry to estimate more accurate Mstars and SFR. We chose SDSS J094700.08+254045.7
(SS 16) for this analysis because it is one of the brightest super spirals in our sample, with good photometry in many
bands, and typical colors. The SDSS spectrum of its bulge is also typical of most super spirals, being dominated by
an old stellar population (Figure A1). We also make a detailed study of 2MASX J13275756+3345291 (SS 05), which
is the most luminous (non-QSO) mid-IR source in our sample and has an SDSS nuclear spectrum with strong young
stellar component and high-equivalent width Hα emission (Figure A2), characteristic of starburst activity.
We remeasured GALEX (FUV, NUV), SDSS (u, g, r, i, z), 2MASS (J, H, Ks) and WISE band 1-4 photometry for
SS 16 using the SAOImager ds9 (Joye & Mandel 2003) on images retrieved from MAST, SDSS, and IRSA (Figure
A3). Aperture and color corrections were applied as necessary and the GALEX and SDSS photometry was corrected
for foreground extinction due to the Milky Way dust (Wyder et al. 2005; Stoughton et al. 2002). The Galactic
extinction is a modest AV = 0.063 mag (NED). We used an elliptical aperture with semimajor and semiminor axes of
31. 5 and 25. 5, respectively, in order to capture the full flux of the spiral disk in all bands. This corresponds to major
and minor diameters of 125 kpc and 102 kpc. We also compute 3σ IRAS upper limits based on the rms uncertainty
measured by IRSA’s Scan Processing and Integration tool (SCANPI) to constrain the FIR luminosity.
We present the SED of SS 16 in Figure A4. The galaxy is detected in all GALEX, SDSS, 2MASS, and WISE bands,
but is undetected by IRAS. The UV through near-IR data points reveal a massive old stellar population plus a young
stellar population. Mid-IR emission appears to be dominated by PAHs and warm dust from star formation. We fit
the SED using magphys template fitting (da Cunha, Charlot, & Elbaz 2008). This gives a total stellar mass of
1.8+0.3
−0.2 × 1011
M and SFR of 9.9+1.6
−0.3M yr−1
. We get a consistent estimate of 1.2 ± 0.1 × 1011
M for the stellar
mass from the u − r color and Ks-band luminosity, applying the Bell et al. (2003) prescription for color-dependent
mass-to-light ratio (Table 1). The WISE band 3 luminosity gives a consistent SFR of 13.5 ± 0.2M yr−1
, using the
prescription of Chang et al. (2015). Lacking FIR detections, we do not have a good handle on the total dust mass,
however, the SED fit formally yields a dust mass of ∼ 108
M , based on the PAH emission and FIR upper limits. This
corresponds to roughly ∼ 1010
M of gas, assuming a standard gas/dust ratio of 100.
We remeasured GALEX (FUV, NUV), SDSS (u, g, r, i, z), 2MASS (J, H, Ks) and WISE band 1-4 photometry
for SS 05 (Figure A5), using a similar procedure. We also retrieved Spitzer IRAC and MIPS, and Herschel PACS and
SPIRE images from the respective IRSA and ESA archives to measure the IR fluxes. We used a circular aperture with
20. 0 (156 kpc) radius for most bands. However, at SPIRE wavelengths, we used the larger point source apertures of
22 , 30 , and 42 , in order to contain the broader point-spread function. The Galactic extinction is only AV = 0.034
mag (NED).
We present the SED of SS 05 in Figure A6. The galaxy is detected in all measured bands except the SPIRE
500 µm band. In contrast to SS 16, there is a stronger component of emission from young stars, and much more
luminous IR emission from star formation activity. We fit the SED using magphys, yielding a total stellar mass of
2.04+0.05
−0.09 × 1011
M and SFR of 40.5+6.5
−0.5M yr−1
. The stellar mass is consistent with the value of 1.6 ± 0.3 × 1011
M
that we obtain from the u − r color and Ks-band luminosity (Table 1). The WISE [12] luminosity gives a somewhat
15. Super Spirals 15
larger SFR of 65 ± 4M yr−1
, using the conversion factor of Chang et al. (2015). The Herschel FIR measurements
yield a secure estimate of total dust mass from the SED fit of 7+3
−1 × 108
M , corresponding to 7 × 1010
M of gas,
assuming a standard gas/dust ratio of 100.
Figure A1. SDSS DR9 optical spectrum and spectral model of SDSS J094700.08+254045.7 (SS 16). Note the possible broad Hα emission
line not fit by the spectral model, indicative of a Seyfert 1 AGN .
Figure A2. SDSS DR9 optical spectrum and spectral model of 2MASX J13275756+334529 (SS 05). The blue spectral slope and strong
Hα emission indicate starburst activity in the galaxy bulge that contributes to the high star formation rate in the galaxy as a whole.
16. 16 Ogle et al.
WISE
12um
4.6um
3.4um
GALEX
NUV
FUV
N
E
20"
2MASS
KsJ H
SDSS
irg
Figure A3. GALEX, SDSS, 2MASS and WISE images of SDSS J094700.08+254045.7 (SS 16). The image scale is 1.991 kpc/ . The
photometric aperture with major and minor axes of 125 kpc and 102 kpc, respectively, is indicated by the ellipse on the SDSS image.
Figure A4. Spectral Energy Distribution of SDSS J094700.08+254045.7 (SS 16) fit by magphys. GALEX (NUV, FUV), SDSS (u, g, r,
i, z), 2MASS (J, H, Ks), and WISE band 1-4 photometry are measured in the aperture shown in A3. IRAS upper limits at 25, 60, and
100 µm are estimated using SCANPI.
17. Super Spirals 17
GALEX
NUV
FUV
N
E
20"
SDSS
irg
IRAC
8.0um
3.6um
4.5um
Herschel
250um
160um
100um
Figure A5. GALEX, SDSS, Spitzer IRAC, and Herschel images of 2MASX J13275756+334529 (SS 05). The image scale is 3.898 kpc/ .
The circular photometric aperture with diameter 156 kpc and two exclusion regions are indicated on the SDSS image.
Figure A6. Spectral Energy Distribution of 2MASX J13275756+334529 (SS 05) fit by magphys. GALEX (NUV, FUV), SDSS (u, g, r,
i, z), 2MASS (J, H, Ks), Spitzer IRAC and MIPS 24, 70, and 160 µm, WISE band 1-4, Herschel PACS 100 and 160 µm, and SPIRE
photometry are measured in the aperture shown in Figure A5. SPIRE 500 µm luminosity is an upper limit.