O telescópio de rastreio VISTA do ESO encontrou uma horda de galáxias massivas anteriormente ocultas por poeira, que existiram quando o Universo era ainda bebê. Ao descobrir e estudar uma grande quantidade deste tipo de galáxias, os astrônomos descobriram, exatamente e pela primeira vez, quando é que tais monstros apareceram pela primeira vez no Universo.
O simples fato de contar o número de galáxias que existem em determinada área do céu permite aos astrônomos testar teorias de formação e evolução galática. No entanto, uma tarefa aparentemente tão fácil torna-se mais difícil quando tentamos contar galáxias cada vez mais distantes e tênues e é mais complicada ainda devido ao fato das galáxias mais brilhantes e fáceis de observar — as mais massivas no Universo — se tornarem mais raras à medida que os astrônomos observam o passado do Universo, enquanto que as galáxias menos brilhantes, mas muito mais numerosas, são ainda mais difíceis de detectar.
Uma equipe de astrônomos liderada por Karina Caputi do Instituto Astronômico Kapteyn da Universidade de Groningen, descobriu muitas galáxias distantes que não tinham sido detectadas anteriormente. A equipe utilizou imagens do rastreioUltraVISTA, um dos seis projetos que usam o VISTA para mapear o céu no infravermelho próximo, e fez um censo das galáxias tênues quando a idade do Universo estava compreendida entre 0,75 e 2,1 bilhões de anos.
O telescópio de rastreio VISTA do ESO encontrou uma horda de galáxias massivas anteriormente ocultas por poeira, que existiram quando o Universo era ainda bebê. Ao descobrir e estudar uma grande quantidade deste tipo de galáxias, os astrônomos descobriram, exatamente e pela primeira vez, quando é que tais monstros apareceram pela primeira vez no Universo.
O simples fato de contar o número de galáxias que existem em determinada área do céu permite aos astrônomos testar teorias de formação e evolução galática. No entanto, uma tarefa aparentemente tão fácil torna-se mais difícil quando tentamos contar galáxias cada vez mais distantes e tênues e é mais complicada ainda devido ao fato das galáxias mais brilhantes e fáceis de observar — as mais massivas no Universo — se tornarem mais raras à medida que os astrônomos observam o passado do Universo, enquanto que as galáxias menos brilhantes, mas muito mais numerosas, são ainda mais difíceis de detectar.
Uma equipe de astrônomos liderada por Karina Caputi do Instituto Astronômico Kapteyn da Universidade de Groningen, descobriu muitas galáxias distantes que não tinham sido detectadas anteriormente. A equipe utilizou imagens do rastreioUltraVISTA, um dos seis projetos que usam o VISTA para mapear o céu no infravermelho próximo, e fez um censo das galáxias tênues quando a idade do Universo estava compreendida entre 0,75 e 2,1 bilhões de anos.
The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are
key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it
is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the
Stardust mission after the flyby at comet Wild 2, the simplest form of amino acids, glycine, has been found
together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples,
a cometary origin was deduced from the 13C isotopic signature. We report the presence of volatile glycine
accompanied by methylamine and ethylamine in the coma of 67P/Churyumov-Gerasimenko measured by
the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the
Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result
demonstrates that comets could have played a crucial role in the emergence of life on Earth.
Evidence for pop_iii_like_stellar_populations_in_the_most_luminous_lyman_alph...Sérgio Sacani
Com o auxílio do Very Large Telescope do ESO, astrônomos descobriram a galáxia mais brilhante observada até hoje no Universo primordial e encontraram evidências fortes de que este objeto contém estrelas da primeira geração. Estas estrelas massivas e brilhantes, puramente teóricas até agora, foram as criadoras dos primeiros elementos pesados na história — os elementos necessários à formação das estrelas que nos rodeiam atualmente, os planetas que as orbitam e a vida tal como a conhecemos. A galáxia recentemente descoberta chamada CR7 é três vezes mais brilhante do que a galáxia distante mais brilhante que era conhecida até agora.
Os astrônomos desenvolveram há algum tempo a teoria da existência de uma primeira geração de estrelas - conhecidas por estrelas de População III — que teriam nascido do material primordial do Big Bang [1]. Todos os elementos químicos mais pesados — como o oxigênio, nitrogênio, carbono e ferro, que são essenciais à vida — formaram-se no interior das estrelas, o que significa que as primeiras estrelas se devem ter formado dos únicos elementos que existiam antes delas: hidrogênio, hélio e traços mínimos de lítio.
Chandra deep observation_of_xdcpj004402033_a_massive_galaxy_cluster_at_z_1_5Sérgio Sacani
Artigo apresenta os resultados obtidos pelo Chandra ao medir com precisão a massa do mais massivo aglomerado de galáxias do universo distante, o Aglomerado Gioiello.
Radial velocity monitoring has found the signature of a Msin i = 1:3 M planet located within the Habitable Zone of Proxima
Centauri, the Sun’s closest neighbor (Anglada-Escudé et al. 2016). Despite a hotter past and an active host star the planet Proxima b
could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016). Here we use a 3D Global Climate Model (GCM)
to simulate Proxima b’s atmosphere and water cycle for its two likely rotation modes (the 1:1 and 3:2 spin-orbit resonances) while
varying the unconstrained surface water inventory and atmospheric greenhouse e ect (represented here with a CO2-N2 atmosphere.)
We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water
inventory larger than 0.6 Earth ocean, liquid water is always present (assuming 1 bar of N2), at least in the substellar region. Liquid
water covers the whole planet for CO2 partial pressures & 1 bar. For smaller water inventories, water can be trapped on the night side,
forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO2
pressure of 10 mbar (assuming 1 bar of N2) is required to avoid falling into a completely frozen snowball state if water is abundant.
If the planet is dryer, 0.5 bar of CO2 would suce to prevent the trapping of any arbitrary small water inventory into polar ice
caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes
discussed here.
We use our GCM to produce reflection/emission spectra and phase curves for the di erent rotations and surface volatile inventories.
We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular
separation of 7=D at 1 m (with the E-ELT) and a contrast of 10 7. The magnitude of the planet will allow for high-resolution
spectroscopy and the search for molecular signatures, including H2O, O2, and CO2.
The observation of thermal phase curves, although challenging, can be attempted with JWST, thanks to a contrast of 210 5 at 10 m.
Proxima b will also be an exceptional target for future IR interferometers. Within a decade it will be possible to image Proxima b and
possibly determine whether this exoplanet’s surface is habitable.
Supermassive black holes in galaxy centres can grow by the accretion
of gas, liberating enormous amounts of energy that might
regulate star formation on galaxy-wide scales1–3
. The nature of
gaseous fuel reservoirs that power black hole growth is nevertheless
largely unconstrained by observations, and is instead routinely
simplified as a smooth, spherical inflow of very hot gas
in accordance with the Bondi solution4
. Recent theory5–7 and
simulations8–10 instead predict that accretion can be dominated by
a stochastic, clumpy distribution of very cold molecular clouds,
though unambiguous observational support for this prediction remains
elusive. Here we show observational evidence for a cold,
clumpy accretion flow toward a supermassive black hole fuel reservoir
in the nucleus of the Abell 2597 Brightest Cluster Galaxy
(BCG), a nearby (z = 0.0821) giant elliptical galaxy surrounded
by a dense halo of hot plasma11–13. Under the right conditions,
thermal instabilities can precipitate from this hot gas, producing a
rain of cold clouds that fall toward the galaxy’s centre14, sustaining
star formation amid a kiloparsec-scale molecular nebula that inhabits
its core15. New interferometric sub-millimetre observations
show that these cold clouds also fuel black hole accretion, revealing
“shadows” cast by molecular clouds as they move inward at ∼ 300
km s−1
toward the active supermassive black hole in the galaxy
centre, which serves as a bright backlight. Corroborating evidence
from prior observations16 of warmer atomic gas at extremely high
spatial resolution17, along with simple arguments based on geometry
and probability, indicates that these clouds are within the innermost
hundred parsecs of the black hole, and falling closer toward
it
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
Aims. We present the first public release of photometric redshifts, galaxy rest frame properties and associated magnification values
in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. The released catalogues aim to
provide a reference for future investigations of extragalactic populations in these legacy fields: from lensed high-redshift galaxies to
cluster members themselves.
Methods.We exploit a multiwavelength catalogue, ranging from Hubble Space Telescope (HST) to ground-based K and Spitzer IRAC,
which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multiband
information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone, or
from a stack of four WFC3 bands. To minimize systematics, median photometric redshifts are assembled from six di erent approaches
to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State-of-the-art lensing
models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts.
Results. We show that photometric redshifts reach a remarkable 3–5% accuracy. After accounting for magnification, the H-band
number counts are found to be in agreement at bright magnitudes with number counts from the CANDELS fields, while extending
the presently available samples to galaxies that, intrinsically, are as faint as H 32 33, thanks to strong gravitational lensing. The
Frontier Fields allow the galaxy stellar mass distribution to be probed, depending on magnification, at 0.5–1.5 dex lower masses with
respect to extragalactic wide fields, including sources at Mstar 107–108 M at z > 5. Similarly, they allow the detection of objects
with intrinsic star formation rates (SFRs) >1 dex lower than in the CANDELS fields reaching 0.1–1 M =yr at z 6–10.
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 Next Generation Transit Survey (NGTS)Sérgio Sacani
We describe the Next Generation Transit Survey (NGTS), which is a ground-based
project searching for transiting exoplanets orbiting bright stars. NGTS builds on the
legacy of previous surveys, most notably WASP, and is designed to achieve higher
photometric precision and hence find smaller planets than have previously been de-
tected from the ground. It also operates in red light, maximising sensitivity to late
K and early M dwarf stars. The survey specifications call for photometric precision
of 0.1 per cent in red light over an instantaneous field of view of 100 square degrees,
enabling the detection of Neptune-sized exoplanets around Sun-like stars and super-
Earths around M dwarfs. The survey is carried out with a purpose-built facility at
Cerro Paranal, Chile, which is the premier site of the European Southern Observatory
(ESO). An array of twelve 20 cm f/2.8 telescopes fitted with back-illuminated deep-
depletion CCD cameras are used to survey fields intensively at intermediate Galactic
latitudes. The instrument is also ideally suited to ground-based photometric follow-up
of exoplanet candidates from space telescopes such as Gaia, TESS and PLATO. We
present observations that combine precise autoguiding and the superb observing con-
ditions at Paranal to provide routine photometric precision of 0.1 per cent in 1 hour
for stars with I-band magnitudes brighter than 13. We describe the instrument and
data analysis methods as well as the status of the survey, which achieved first light
in 2015 and began full survey operations in 2016. NGTS data will be made publicly
available through the ESO archive.
The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are
key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it
is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the
Stardust mission after the flyby at comet Wild 2, the simplest form of amino acids, glycine, has been found
together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples,
a cometary origin was deduced from the 13C isotopic signature. We report the presence of volatile glycine
accompanied by methylamine and ethylamine in the coma of 67P/Churyumov-Gerasimenko measured by
the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the
Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result
demonstrates that comets could have played a crucial role in the emergence of life on Earth.
Evidence for pop_iii_like_stellar_populations_in_the_most_luminous_lyman_alph...Sérgio Sacani
Com o auxílio do Very Large Telescope do ESO, astrônomos descobriram a galáxia mais brilhante observada até hoje no Universo primordial e encontraram evidências fortes de que este objeto contém estrelas da primeira geração. Estas estrelas massivas e brilhantes, puramente teóricas até agora, foram as criadoras dos primeiros elementos pesados na história — os elementos necessários à formação das estrelas que nos rodeiam atualmente, os planetas que as orbitam e a vida tal como a conhecemos. A galáxia recentemente descoberta chamada CR7 é três vezes mais brilhante do que a galáxia distante mais brilhante que era conhecida até agora.
Os astrônomos desenvolveram há algum tempo a teoria da existência de uma primeira geração de estrelas - conhecidas por estrelas de População III — que teriam nascido do material primordial do Big Bang [1]. Todos os elementos químicos mais pesados — como o oxigênio, nitrogênio, carbono e ferro, que são essenciais à vida — formaram-se no interior das estrelas, o que significa que as primeiras estrelas se devem ter formado dos únicos elementos que existiam antes delas: hidrogênio, hélio e traços mínimos de lítio.
Chandra deep observation_of_xdcpj004402033_a_massive_galaxy_cluster_at_z_1_5Sérgio Sacani
Artigo apresenta os resultados obtidos pelo Chandra ao medir com precisão a massa do mais massivo aglomerado de galáxias do universo distante, o Aglomerado Gioiello.
Radial velocity monitoring has found the signature of a Msin i = 1:3 M planet located within the Habitable Zone of Proxima
Centauri, the Sun’s closest neighbor (Anglada-Escudé et al. 2016). Despite a hotter past and an active host star the planet Proxima b
could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016). Here we use a 3D Global Climate Model (GCM)
to simulate Proxima b’s atmosphere and water cycle for its two likely rotation modes (the 1:1 and 3:2 spin-orbit resonances) while
varying the unconstrained surface water inventory and atmospheric greenhouse e ect (represented here with a CO2-N2 atmosphere.)
We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water
inventory larger than 0.6 Earth ocean, liquid water is always present (assuming 1 bar of N2), at least in the substellar region. Liquid
water covers the whole planet for CO2 partial pressures & 1 bar. For smaller water inventories, water can be trapped on the night side,
forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO2
pressure of 10 mbar (assuming 1 bar of N2) is required to avoid falling into a completely frozen snowball state if water is abundant.
If the planet is dryer, 0.5 bar of CO2 would suce to prevent the trapping of any arbitrary small water inventory into polar ice
caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes
discussed here.
We use our GCM to produce reflection/emission spectra and phase curves for the di erent rotations and surface volatile inventories.
We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular
separation of 7=D at 1 m (with the E-ELT) and a contrast of 10 7. The magnitude of the planet will allow for high-resolution
spectroscopy and the search for molecular signatures, including H2O, O2, and CO2.
The observation of thermal phase curves, although challenging, can be attempted with JWST, thanks to a contrast of 210 5 at 10 m.
Proxima b will also be an exceptional target for future IR interferometers. Within a decade it will be possible to image Proxima b and
possibly determine whether this exoplanet’s surface is habitable.
Supermassive black holes in galaxy centres can grow by the accretion
of gas, liberating enormous amounts of energy that might
regulate star formation on galaxy-wide scales1–3
. The nature of
gaseous fuel reservoirs that power black hole growth is nevertheless
largely unconstrained by observations, and is instead routinely
simplified as a smooth, spherical inflow of very hot gas
in accordance with the Bondi solution4
. Recent theory5–7 and
simulations8–10 instead predict that accretion can be dominated by
a stochastic, clumpy distribution of very cold molecular clouds,
though unambiguous observational support for this prediction remains
elusive. Here we show observational evidence for a cold,
clumpy accretion flow toward a supermassive black hole fuel reservoir
in the nucleus of the Abell 2597 Brightest Cluster Galaxy
(BCG), a nearby (z = 0.0821) giant elliptical galaxy surrounded
by a dense halo of hot plasma11–13. Under the right conditions,
thermal instabilities can precipitate from this hot gas, producing a
rain of cold clouds that fall toward the galaxy’s centre14, sustaining
star formation amid a kiloparsec-scale molecular nebula that inhabits
its core15. New interferometric sub-millimetre observations
show that these cold clouds also fuel black hole accretion, revealing
“shadows” cast by molecular clouds as they move inward at ∼ 300
km s−1
toward the active supermassive black hole in the galaxy
centre, which serves as a bright backlight. Corroborating evidence
from prior observations16 of warmer atomic gas at extremely high
spatial resolution17, along with simple arguments based on geometry
and probability, indicates that these clouds are within the innermost
hundred parsecs of the black hole, and falling closer toward
it
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
Aims. We present the first public release of photometric redshifts, galaxy rest frame properties and associated magnification values
in the cluster and parallel pointings of the first two Frontier Fields, Abell-2744 and MACS-J0416. The released catalogues aim to
provide a reference for future investigations of extragalactic populations in these legacy fields: from lensed high-redshift galaxies to
cluster members themselves.
Methods.We exploit a multiwavelength catalogue, ranging from Hubble Space Telescope (HST) to ground-based K and Spitzer IRAC,
which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions. The multiband
information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone, or
from a stack of four WFC3 bands. To minimize systematics, median photometric redshifts are assembled from six di erent approaches
to photo-z estimates. Their reliability is assessed through a comparison with available spectroscopic samples. State-of-the-art lensing
models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts.
Results. We show that photometric redshifts reach a remarkable 3–5% accuracy. After accounting for magnification, the H-band
number counts are found to be in agreement at bright magnitudes with number counts from the CANDELS fields, while extending
the presently available samples to galaxies that, intrinsically, are as faint as H 32 33, thanks to strong gravitational lensing. The
Frontier Fields allow the galaxy stellar mass distribution to be probed, depending on magnification, at 0.5–1.5 dex lower masses with
respect to extragalactic wide fields, including sources at Mstar 107–108 M at z > 5. Similarly, they allow the detection of objects
with intrinsic star formation rates (SFRs) >1 dex lower than in the CANDELS fields reaching 0.1–1 M =yr at z 6–10.
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 Next Generation Transit Survey (NGTS)Sérgio Sacani
We describe the Next Generation Transit Survey (NGTS), which is a ground-based
project searching for transiting exoplanets orbiting bright stars. NGTS builds on the
legacy of previous surveys, most notably WASP, and is designed to achieve higher
photometric precision and hence find smaller planets than have previously been de-
tected from the ground. It also operates in red light, maximising sensitivity to late
K and early M dwarf stars. The survey specifications call for photometric precision
of 0.1 per cent in red light over an instantaneous field of view of 100 square degrees,
enabling the detection of Neptune-sized exoplanets around Sun-like stars and super-
Earths around M dwarfs. The survey is carried out with a purpose-built facility at
Cerro Paranal, Chile, which is the premier site of the European Southern Observatory
(ESO). An array of twelve 20 cm f/2.8 telescopes fitted with back-illuminated deep-
depletion CCD cameras are used to survey fields intensively at intermediate Galactic
latitudes. The instrument is also ideally suited to ground-based photometric follow-up
of exoplanet candidates from space telescopes such as Gaia, TESS and PLATO. We
present observations that combine precise autoguiding and the superb observing con-
ditions at Paranal to provide routine photometric precision of 0.1 per cent in 1 hour
for stars with I-band magnitudes brighter than 13. We describe the instrument and
data analysis methods as well as the status of the survey, which achieved first light
in 2015 and began full survey operations in 2016. NGTS data will be made publicly
available through the ESO archive.
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.
Galaxy growth in a massive halo in the first billion years of cosmic historySérgio Sacani
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field1–3. Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far4,5. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey6. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe7. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.
An excess of_dusty_starbusts_related_to_the_spiderweb_galaxySérgio Sacani
Artigo que descreve as últimas observações do APEX revelando como se dá a formação de estrelas e a construção do Aglomerado de Galáxias da Teia de Aranha.
GOALS-JWST: Unveiling Dusty Compact Sources in the Merging Galaxy IIZw096Sérgio Sacani
We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first
spatially resolved, mid-infrared images of IIZw096, a merging luminous infrared galaxy (LIRG) at z = 0.036.
Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity
(LIR) of the system originated from a small region outside of the two merging nuclei. New observations with
JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is
responsible for the bulk of the IR emission. We estimate that 40%–70% of the IR bolometric luminosity, or
3–5 × 1011 Le, arises from a source no larger than 175 pc in radius, suggesting a luminosity density of at least
3–5 × 1012 Le kpc−2
. In addition, we detect 11 other star-forming sources, five of which were previously
unknown. The MIRI F1500W/F560W colors of most of these sources, including the source responsible for the
bulk of the far-IR emission, are much redder than the nuclei of local LIRGs. These observations reveal the power
of JWST to disentangle the complex regions at the hearts of merging, dusty galaxies.
Discovery and properties of the earliest galaxies with confirmed distancesSérgio Sacani
Surveys with James Webb Space Telescope (JWST) have discovered candidate galaxies in
the first 400 Myr of cosmic time1-5
. The properties of these distant galaxies provide initial
conditions for understanding early galaxy formation and cosmic reionisation6
. Preliminary
indications have suggested these candidate galaxies may be more massive and abundant
than previously thought1,7-9
. However, without spectroscopic confirmation of their
distances to constrain their intrinsic brightnesses, their inferred properties remain
uncertain. Here we report on four galaxies located in the JWST Advanced Deep
Extragalactic Survey (JADES) Near-Infrared Camera (NIRCam) imaging with
photometric redshifts � ∼ �� − �� subsequently confirmed by JADES JWST NearInfrared Spectrograph (NIRSpec) observations10. These galaxies include the first redshift
� > �� systems both discovered and spectroscopically confirmed by JWST. Using stellar
population modelling, we find the galaxies typically contain a hundred million solar masses
in stars, in stellar populations that are less than one hundred million years old. The
moderate star formation rates and compact sizes suggest elevated star formation rate
surface densities, a key indicator of their formation pathways. Taken together, these
measurements show that the first galaxies contributing to cosmic reionisation formed
rapidly and with intense internal radiation fields.
An excess of massive stars in the local 30 Doradus starburstSérgio Sacani
The 30 Doradus star-forming region in the Large Magellanic Cloud is a nearby analog of large
star-formation events in the distant universe.We determined the recent formation history and
the initial mass function (IMF) of massive stars in 30 Doradus on the basis of spectroscopic
observations of 247 stars more massive than 15 solarmasses (M⊙).Themain episode of massive
star formation began about 8 million years (My) ago, and the star-formation rate seems to
have declined in the last 1 My.The IMF is densely sampled up to 200M⊙ and contains 32 ± 12%
more stars above 30 M⊙ than predicted by a standard Salpeter IMF. In the mass range of 15
to 200M⊙, the IMF power-law exponent is 1:90þ0:37
0:26, shallower than the Salpeter value of 2.35.
Phosphine gas in the cloud decks of VenusSérgio Sacani
Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our
nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine
(PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband
spectral detections (quality up to ~15σ) from the JCMT and ALMA telescopes have no other plausible identification. Atmospheric
PH3 at ~20 ppb abundance is inferred. The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and
photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and subsurface,
or from lightning, volcanic or meteoritic delivery. PH3 could originate from unknown photochemistry or geochemistry,
or, by analogy with biological production of PH3 on Earth, from the presence of life. Other PH3 spectral features should be
sought, while in situ cloud and surface sampling could examine sources of this gas.
A dusty star-forming galaxy at z = 6 revealed by strong gravitational lensingSérgio Sacani
Since their discovery, submillimetre-selected galaxies1,2
have revolutionized the field of galaxy formation and evolution.
From the hundreds of square degrees mapped at submillimetre
wavelengths3–5
, only a handful of sources have
been confirmed to lie at z> 5 (refs 6–10) and only two at z ≥ 6
(refs 11,12). All of these submillimetre galaxies are rare examples
of extreme starburst galaxies with star formation rates
of ≳1,000 M⊙ yr−1
and therefore are not representative
of the general population of dusty star-forming galaxies.
Consequently, our understanding of the nature of these
sources, at the earliest epochs, is still incomplete. Here, we
report the spectroscopic identification of a gravitationally
amplified (μ= 9.3 ± 1.0) dusty star-forming galaxy at z= 6.027.
After correcting for gravitational lensing, we derive an intrinsic
less-extreme star formation rate of 380 ± 50 M⊙ yr−1
for this source and find that its gas and dust properties are
similar to those measured for local ultra luminous infrared
galaxies, extending the local trends to a poorly explored territory
in the early Universe. The star-formation efficiency
of this galaxy is similar to those measured in its local analogues13,
despite a ~12 Gyr difference in cosmic time.
The most luminous_galaxies_discovered_by_wiseSérgio Sacani
Artigo descreve estudo feito por astrônomos e com a ajuda da sonda WISE da NASA para identificar as galáxias do tipo ELIRGs, entre elas a mais luminosa galáxia do universo, com um buraco negro gigantesco em seu interior e localizada a cerca de 12.8 bilhões de anos de distância da Terra.
XUE: Molecular Inventory in the Inner Region of an Extremely Irradiated Proto...Sérgio Sacani
We present the first results of the eXtreme UV Environments (XUE) James Webb Space Telescope (JWST)
program, which focuses on the characterization of planet-forming disks in massive star-forming regions. These
regions are likely representative of the environment in which most planetary systems formed. Understanding the
impact of environment on planet formation is critical in order to gain insights into the diversity of the observed
exoplanet populations. XUE targets 15 disks in three areas of NGC 6357, which hosts numerous massive OB stars,
including some of the most massive stars in our Galaxy. Thanks to JWST, we can, for the first time, study the effect
of external irradiation on the inner (<10 au), terrestrial-planet-forming regions of protoplanetary disks. In this study,
we report on the detection of abundant water, CO, 12CO2, HCN, and C2H2 in the inner few au of XUE 1, a highly
irradiated disk in NGC 6357. In addition, small, partially crystalline silicate dust is present at the disk surface. The
derived column densities, the oxygen-dominated gas-phase chemistry, and the presence of silicate dust are
surprisingly similar to those found in inner disks located in nearby, relatively isolated low-mass star-forming
regions. Our findings imply that the inner regions of highly irradiated disks can retain similar physical and chemical
conditions to disks in low-mass star-forming regions, thus broadening the range of environments with similar
conditions for inner disk rocky planet formation to the most extreme star-forming regions in our Galaxy.
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 JWST Discovery of the Triply-imaged Type Ia “Supernova H0pe” and Observat...Sérgio Sacani
A Type Ia supernova (SN) at z = 1.78 was discovered in James Webb Space Telescope Near Infrared
Camera imaging of the galaxy cluster PLCK G165.7+67.0 (G165; z = 0.35). The SN is situated 1.5–
2 kpc from its host galaxy Arc 2 and appears in three different locations as a result of gravitational
lensing by G165. These data can yield a value for Hubble’s constant using time delays from this
multiply-imaged SN Ia that we call “SN H0pe.” Over the entire field we identified 21 image multiplicities,
confirmed five of them using Near-Infrared Spectrograph (NIRspec), and constructed a new
lens model that gives a total mass within 600 kpc of (2.6 ± 0.3) × 1014M⊙. The photometry uncovered
a galaxy overdensity at Arc 2’s redshift. NIRSpec confirmed six member galaxies, four of which
surround Arc 2 with relative velocity ≲900 km s−1 and projected physical extent ≲33 kpc. Arc 2
dominates the stellar mass ((5.0±0.1)×1011M⊙), which is a factor of ten higher than other members
of this compact galaxy group. These other group members have specific star formation rates (sSFR)
arXiv:2309.07326v1 [astro-ph.GA] 13 Sep 2023
2 Frye, Pascale, Pierel et al.
of 2–260 Gyr−1 derived from the Hα-line flux corrected for stellar absorption, dust extinction, and slit
losses. Another group centered on the dusty star forming galaxy Arc 1 is at z = 2.24. The total SFR
for the Arc 1 group (≳400M⊙ yr−1) translates to a supernova rate of ∼1 SNe yr−1, suggesting that
regular monitoring of this cluster may yield additional SNe.
An irradiated-Jupiter analogue hotter than the SunSérgio Sacani
Planets orbiting close to hot stars experience intense extreme-ultraviolet
radiation, potentially leading to atmosphere evaporation and to thermal
dissociation of molecules. However, this extreme regime remains mainly
unexplored due to observational challenges. Only a single known ultra-hot
giant planet, KELT-9b, receives enough ultraviolet radiation for molecular
dissociation, with a day-side temperature of ~4,600 K. An alternative
approach uses irradiated brown dwarfs as hot-Jupiter analogues. With
atmospheres and radii similar to those of giant planets, brown dwarfs
orbiting close to hot Earth-sized white dwarf stars can be directly detected
above the glare of the star. Here we report observations revealing
an extremely irradiated low-mass companion to the hot white dwarf
WD 0032–317. Our analysis indicates a day-side temperature of ~8,000 K,
and a day-to-night temperature difference of ~6,000 K. The amount of
extreme-ultraviolet radiation (with wavelengths 100–912 Å) received by
WD 0032–317B is equivalent to that received by planets orbiting close to stars
as hot as late B-type stars, and about 5,600 times higher than that of KELT-9b.
With a mass of ~75–88 Jupiter masses, this near-hydrogen-burning-limit
object is potentially one of the most massive brown dwarfs known.
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.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
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![LETTER doi:10.1038/nature12050
A dust-obscured massive maximum-starburst
galaxy at a redshift of 6.34
Dominik A. Riechers1,2, C. M. Bradford1,3, D. L. Clements4, C. D. Dowell1,3, I. Perez-Fournon5,6, R. J. Ivison7,8, C. Bridge1,
´
A. Conley9, Hai Fu10, J. D. Vieira1, J. Wardlow10, J. Calanog10, A. Cooray1,10, P. Hurley11, R. Neri12, J. Kamenetzky13, J. E. Aguirre14,
B. Altieri15, V. Arumugam8, D. J. Benford16, M. Bethermin17,18, J. Bock1,3, D. Burgarella19, A. Cabrera-Lavers5,6,20, S. C. Chapman21,
´
P. Cox12, J. S. Dunlop8, L. Earle9, D. Farrah22, P. Ferrero5,6, A. Franceschini23, R. Gavazzi24, J. Glenn9,13, E. A. Gonzalez Solares21,
M. A. Gurwell25, M. Halpern26, E. Hatziminaoglou27, A. Hyde4, E. Ibar7, A. Kovacs1,28, M. Krips12, R. E. Lupu14, P. R. Maloney9,
´
P. Martinez-Navajas5,6, H. Matsuhara29, E. J. Murphy1,30, B. J. Naylor3, H. T. Nguyen1,3, S. J. Oliver11, A. Omont24, M. J. Page31,
G. Petitpas25, N. Rangwala13, I. G. Roseboom8,11, D. Scott26, A. J. Smith11, J. G. Staguhn16,32, A. Streblyanska5,6, A. P. Thomson8,
I. Valtchanov15, M. Viero1, L. Wang11, M. Zemcov1,3 & J. Zmuidzinas1,3
Massive present-day early-type (elliptical and lenticular) galaxies of number counts in the Herschel/SPIRE bands suggest a space
probably gained the bulk of their stellar mass and heavy elements density of massive starburst galaxies at z . 6 with S500mm . 30 mJy
through intense, dust-enshrouded starbursts—that is, increased of 0.014 deg22 (ref. 7).
rates of star formation—in the most massive dark-matter haloes To understand the nature of galaxies selected by this technique, we
at early epochs. However, it remains unknown how soon after the have obtained full frequency scans of the 3-mm and 1-mm bands
Big Bang massive starburst progenitors exist. The measured red- towards HFLS 3 (also known as 1HERMES S350 J170647.81584623;
shift (z) distribution of dusty, massive starbursts has long been S500mm/S350mm 5 1.45), the brightest candidate discovered in our study.
suspected to be biased low in z owing to selection effects1, as con- These observations, augmented by selected follow-up over a broader
firmed by recent findings of systems with redshifts as high as 5 wavelength range, unambiguously determine the galaxy redshift to be
(refs 2–4). Here we report the identification of a massive starburst z 5 6.3369 6 0.0009 based on a suite of 7 CO lines, 7 H2O lines, and
galaxy at z 5 6.34 through a submillimetre colour-selection tech- OH, OH1, H2O1, NH3, [C I] and [C II] lines detected in emission and
nique. We unambiguously determined the redshift from a suite of absorption (Fig. 1). At this redshift, the Universe was just 880 million
molecular and atomic fine-structure cooling lines. These measure- years old (or one-sixteenth of its present age), and 10 on the sky corre-
ments reveal a hundred billion solar masses of highly excited, sponds to a physical scale of 5.6 kpc. Further observations from optical
chemically evolved interstellar medium in this galaxy, which con- to radio wavelengths reveal strong continuum emission over virtually
stitutes at least 40 per cent of the baryonic mass. A ‘maximum the entire wavelength range between 2.2 mm and 20 cm, with no
starburst’ converts the gas into stars at a rate more than 2,000 times detected emission shortward of 1 mm (see Supplementary Informa-
that of the Milky Way, a rate among the highest observed at any tion section 2 and Supplementary Figs 1–11 for additional details).
epoch. Despite the overall downturn in cosmic star formation HFLS 3 hosts an intense starburst. The 870-mm flux of HFLS 3 is
towards the highest redshifts5, it seems that environments mature .3.5 times higher than those of the brightest high-redshift starbursts
enough to form the most massive, intense starbursts existed at least in a 0.25-deg2 region containing the Hubble Ultra Deep Field (HUDF)8.
as early as 880 million years after the Big Bang. From the continuum spectral energy distribution (Fig. 2), we find that
We have searched 21 deg2 of the Herschel/SPIRE data of the the far-infrared (FIR) luminosity LFIR and inferred star formation rate
HerMES blank field survey6 at wavelengths 250–500 mm for ‘ultra- (SFR) of 2,900 Msun yr21 of HFLS 3 (where Msun is the solar mass) are 15–
red’ sources with flux densities S250mm , S350mm , S500mm and S500mm/ 20 times those of the prototypical local ultra-luminous starburst Arp 220,
S350mm . 1.3, that is, galaxies that are significantly redder (and thus, and .2,000 times those of the Milky Way (Table 1 and Supplementary
potentially at higher redshift) than massive starbursts discovered thus Information section 3). The SFR of HFLS 3 alone corresponds to ,4.5
far. This selection yields five candidate ultra-red sources down to a flux times the ultraviolet-based SFR of all z 5 5.5–6.5 star-forming galaxies in
limit of 30 mJy at 500 mm (.5s and above the confusion noise; see the HUDF combined9, but the rarity and dust obscuration of ultra-red
Supplementary Information section 1 for additional details), corres- sources like HFLS 3 implies that they do not dominate the ultraviolet
ponding to a source density of #0.24 deg22. For comparison, models photon density needed to reionize the Universe10.
1
California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, California 91125, USA. 2Cornell University, 220 Space Sciences Building, Ithaca, New York 14853, USA. 3Jet
Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109, USA. 4Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK. 5Instituto
de Astrofisica de Canarias, E-38200 La Laguna, Tenerife, Spain. 6Departamento de Astrofisica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain. 7UK Astronomy Technology Centre, Royal
Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK. 8Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK. 9Center for Astrophysics and Space
Astronomy 389-UCB, University of Colorado, Boulder, Colorado 80309, USA. 10Department of Physics and Astronomy, University of California, Irvine, California 92697, USA. 11Astronomy Centre,
Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK. 12Institut de RadioAstronomie Millimetrique, 300 Rue de la Piscine, Domaine Universitaire, F-38406 Saint Martin
d’Heres, France. 13Department of Astrophysical and Planetary Sciences, CASA 389-UCB, University of Colorado, Boulder, Colorado 80309, USA. 14Department of Physics and Astronomy, University of
Pennsylvania, Philadelphia, Pennsylvania 19104, USA. 15Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Canada, 28691 Madrid, Spain. 16Observational Cosmology
˜
Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. 17Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Universite Paris Diderot, CEA Saclay, Point courrier
´
131, F-91191 Gif-sur-Yvette, France. 18Institut d’Astrophysique Spatiale (IAS), Ba ˆtiment 121, Universite Paris-Sud 11 and CNRS, UMR 8617, F-91405 Orsay, France. 19Aix-Marseille Universite, CNRS,
´
Laboratoire d’Astrophysique de Marseille, UMR7326, F-13388 Marseille, France. 20Grantecan S.A., Centro de Astrofısica de La Palma, Cuesta de San Jose, E-38712 Brena Baja, La Palma, Spain. 21Institute
´
22 23
of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK. Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA. Dipartimento di Fisica e Astronomia,
Universita di Padova, vicolo Osservatorio 3, I-35122 Padova, Italy. 24Institut d’Astrophysique de Paris, UMR 7095, CNRS, UPMC Univ. Paris 06, 98bis Boulevard Arago, F-75014 Paris, France. 25Harvard-
`
Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA. 26Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road,
Vancouver, British Columbia V6T 1Z1, Canada. 27ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Munchen, Germany. 28Institute for Astrophysics, University of Minnesota, 116 Church Street
¨
Southeast, Minneapolis, Minnesota 55455, USA. 29Institute for Space and Astronautical Science, Japan Aerospace and Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan. 30Infrared Processing
and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, California 91125, USA. 31Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT,
UK. 32Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
1 8 A P R I L 2 0 1 3 | VO L 4 9 6 | N AT U R E | 3 2 9
©2013 Macmillan Publishers Limited. All rights reserved](https://image.slidesharecdn.com/adustobscuredmassivemaximumstarburstgalaxyataredshift634-130417193438-phpapp02/85/A-dust-obscured_massive_maximum_starburst_galaxy_at_a_redshift_634-1-320.jpg)
![RESEARCH LETTER
a 30
HFLS3 (z=6.3369) [C II] [O I]
25 Arp 220 (z=0.0181)
Unlabelled lines, H2O
1.0 [N II] OH
b c d
CO H2O
20
CO
Flux density (mJy)
0.5
CO
15
0.0
150 200 250 300 35 0
H 2O
10 H2O NH
CO
H2O
CO NH3
CO H2O OH+
5 CO H2O
[C I]
H2O+
CO
0
e f g h ij k l m n o
600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200
νrest (GHz)
b c d e f g h
0.8 6.0 CO(J=6–5)
0.4 CO(J=1–0) CO(J=2–1) CO(J=3–2) H2O(211–202) 6.0 CO(J=7–6) and [C I] 6.0 H2O(202–111)
1.2 4.0
H2O+H2O+
4.0
0.2 0.4 0.8 4.0
4.0
2.0
2.0
0.0 0.4 2.0
0.0 2.0
0.0 0.0
–0.2 0.0 0.0
00
0
0
00
00
0
0
0
00
0
0
0
0
–2 0
00
0
0
0
00
0
0
00
00
0
0
0
00
00
0
0
00
00
00
00
00
00
0
00
00
00
00
00
00
,0
,0
,0
,0
,0
,0
,0
,0
,0
,0
,0
2,
2,
4,
2,
4,
6,
2,
4,
5,
2,
4,
2,
–2
–4
–2
–2
–4
–5
–4
–2
–4
–2
i j k 15
l m n 60
o
8.0 OH+(1 –0 ) 8.0 H O(3 –3 ) OH(2Π1/2 J=3/2–1/2)
8.0 CO(J=9–8) 12 12 2 12 03 CO(J=10–9) 17 NH3(3,K)a–(2,K)s [C II](2P3/2–2P1/2)
CO(J=9–8) 25 [–/+] [+/–]
H2O(321–312) K=2,1,0
CO(J=16–15)
16 40
6.0 6.0 OH+ 6.0
OH+ 10
15 20
4.0 4.0 4.0 20
14
5
15
2.0 2.0 13
2.0 0
00
00
0
0
00
00
0
00
0
0
0
00
00
0
00
00
0
0
00
0
0
0
00
0
0
0
0
00
00
00
00
00
00
00
00
00
,0
,0
,0
,0
,0
,0
,0
,0
,0
,0
,0
2,
2,
4,
1,
1,
2,
1,
2,
2,
–4
–2
–4
–2
–2
–4
–2
–2
–1
–1
–1
Velocity offset (km s–1)
Figure 1 | Redshift identification through molecular and atomic (CARMA) not shown in a. The line profiles are typically asymmetric relative to
spectroscopy of HFLS 3. a, Black trace, wide-band spectroscopy in the single Gaussian fits, indicating the presence of two principal velocity
observed-frame 19–0.95-mm (histogram; rest-frame 2,600–130 mm) components at redshifts of 6.3335 and 6.3427. The implied CO, [C I] and [C II]
wavelength range with CARMA (3 mm; ‘blind’ frequency scan of the full band), line luminosities are respectively (5.08 6 0.45) 3 106 Lsun,
the PdBI (2 mm), the JVLA (19–6 mm) and CSO/Z-spec (1 mm; instantaneous (3.0 6 1.9) 3 108 Lsun and (1.55 6 0.32) 3 1010 Lsun. Strong rest-frame
coverage). (CARMA, Combined Array for Research in Millimeter-wave submillimetre to FIR continuum emission is detected over virtually the entire
Astronomy; PdBI, Plateau de Bure Interferometer; JVLA, Jansky Very Large wavelength range. For comparison, the Herschel/SPIRE spectrum of the nearby
Array; and CSO, Caltech Submillimeter Observatory.) This uniquely ultra-luminous infrared galaxy Arp 22020 is overplotted in grey (a). Lines
determines the redshift of HFLS 3 to be z 5 6.3369 based on the detection of a labelled in italic are tentative detections or upper limits (see Supplementary
series of H2O, CO, OH, OH1, NH3, [C I] and [C II] emission and absorption Table 2). Most of the bright spectral features detected in Arp 22020,21 are also
lines. b–o, Detailed profiles of detected lines (histograms; rest frequencies are detected in HFLS 3 (in spectral regions not blocked by the terrestrial
indicated by corresponding letters in a). 1-mm lines (m–o) are deeper, atmosphere). See Supplementary Information sections 2–4 for more details.
interferometric confirmation observations for NH3, OH (both PdBI) and [C II]
HFLS 3 is a massive, gas-rich galaxy. From the spectral energy distri- gas mass fraction in galaxies is a measure of the relative depletion and
bution and the intensity of the CO and [C II] emission, we find a dust replenishment of molecular gas, and is expected to be a function of halo
mass of Md 5 1.3 3 109 Msun and total molecular and atomic gas masses mass and redshift from simulations14. In HFLS 3, we find a high gas mass
of respectively Mgas 5 1.0 3 1011 Msun and MHI 5 2.0 3 1010 Msun. These fraction of fgas 5 Mgas/Mdyn < 40%, comparable to what is found in sub-
masses are 15–20 times those of Arp 220, and correspond to a gas-to- millimetre-selected starbursts and massive star-forming galaxies at z < 2
dust ratio of ,80 and a gas depletion timescale of Mgas/SFR < 36 Myr. (refs 15, 16), but ,3 times higher than in nearby ultra-luminous infrared
These values are comparable to lower-redshift submillimetre-selected galaxies (ULIRGs) like Arp 220, and .30 times higher than in the Milky
starbursts11,12. From the [C I] luminosity, we find an atomic carbon mass Way. From population synthesis modelling, we find a stellar mass of
of 4.5 3 107 Msun. At the current SFR of HFLS 3, this level of carbon M* 5 3.7 3 1010 Msun, comparable to that of Arp 220 and about half that
enrichment could have been achieved through supernovae on a timescale of the Milky Way. This suggests that at most ,40% of Mdyn within the
of ,107 yr (ref. 13). The profiles of the molecular and atomic emission radius of the gas reservoir is due to dark matter. With up to ,1011 Msun of
lines typically show two velocity components (Fig. 1 and Supplementary dark matter within 3.4 kpc, HFLS 3 is likely to reside in a dark-matter halo
Figs 5 and 7). The gas is distributed over a region of 1.7 kpc radius with a massive enough to grow a present-day galaxy cluster17. The efficiency
high velocity gradient and dispersion (Fig. 3). This suggests a dispersion- of star formation is given by e 5 tdyn 3 SFR/Mgas, where tdyn 5 (r3/
dominated galaxy with a dynamical mass of Mdyn 5 2.7 3 1011 Msun. The (2GM))1/2 is the dynamical (or free-fall) time, r is the source radius,
3 3 0 | N AT U R E | VO L 4 9 6 | 1 8 A P R I L 2 0 1 3
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