1) Researchers observed an optical flash and fading afterglow from the powerful gamma-ray burst GRB 130427A. 2) The optical and gamma-ray (>100 MeV) light curves were closely correlated during the first 7,000 seconds, best explained by reverse shock emission generated in the relativistic ejecta. 3) At later times, the optical light showed evidence of forward shock emission as it interacted with the surrounding environment.
A gravitational-wave standard siren measurement of the Hubble constantSérgio Sacani
On 17 August 2017, the Advanced LIGO1
and Virgo2
detectors
observed the gravitational-wave event GW170817—a strong signal
from the merger of a binary neutron-star system3
. Less than two
seconds after the merger, a γ-ray burst (GRB 170817A) was detected
within a region of the sky consistent with the LIGO–Virgo-derived
location of the gravitational-wave source4–6. This sky region was
subsequently observed by optical astronomy facilities7
, resulting
in the identification8–13 of an optical transient signal within
about ten arcseconds of the galaxy NGC 4993. This detection of
GW170817 in both gravitational waves and electromagnetic waves
represents the first ‘multi-messenger’ astronomical observation.
Such observations enable GW170817 to be used as a ‘standard
siren’14–18 (meaning that the absolute distance to the source can be
determined directly from the gravitational-wave measurements)
to measure the Hubble constant. This quantity represents the local
expansion rate of the Universe, sets the overall scale of the Universe
and is of fundamental importance to cosmology. Here we report a
measurement of the Hubble constant that combines the distance
to the source inferred purely from the gravitational-wave signal
with the recession velocity inferred from measurements of the
redshift using the electromagnetic data. In contrast to previous
measurements, ours does not require the use of a cosmic ‘distance
ladder’19: the gravitational-wave analysis can be used to estimate
the luminosity distance out to cosmological scales directly, without
the use of intermediate astronomical distance measurements. We
determine the Hubble constant to be about 70 kilometres per
second per megaparsec. This value is consistent with existing
measurements20,21, while being completely independent of them.
Additional standard siren measurements from future gravitationalwave
sources will enable the Hubble constant to be constrained to
high precision.
Polarized reflected light from the Spica binary systemSérgio Sacani
Close binary systems often show linear polarization varying
over the binary period, usually attributed to light scattered
from electrons in circumstellar clouds1–3
. One of the brightest
close binary systems is Spica (alpha Virginis) consisting of
two B-type stars orbiting with a period of just over four days.
Past observations of Spica have shown low polarization with
no evidence for variability4–6. Here we report new high-precision polarization observations of Spica that show variation
with an amplitude of about 200 parts per million. By including
polarized radiative transfer in a binary star model, we show
that the phase-dependent polarization is mainly due to light
reflected from the primary component of the binary system
off the secondary component and vice versa. The stars reflect
only a few per cent of the incident light, but the reflected light
is very highly polarized. The polarization results show that the
binary orbit is clockwise and the position angle of the line of
nodes is 130.4° ± 6.8°, in agreement with intensity interferometer results7
. We suggest that reflected light polarization
may be much more important in binary systems than has previously been recognized and may be a way of detecting previously unrecognized close binaries.
Convective storms in Europe: a look back at COPS and CSIPAndrew Russell
A seminar given at RMS in London on 16th March on the main results from the Convective Storm Initiation Project (CSIP) and the Convective and Orographically-induced Precipitation Study (COPS).
A gravitational-wave standard siren measurement of the Hubble constantSérgio Sacani
On 17 August 2017, the Advanced LIGO1
and Virgo2
detectors
observed the gravitational-wave event GW170817—a strong signal
from the merger of a binary neutron-star system3
. Less than two
seconds after the merger, a γ-ray burst (GRB 170817A) was detected
within a region of the sky consistent with the LIGO–Virgo-derived
location of the gravitational-wave source4–6. This sky region was
subsequently observed by optical astronomy facilities7
, resulting
in the identification8–13 of an optical transient signal within
about ten arcseconds of the galaxy NGC 4993. This detection of
GW170817 in both gravitational waves and electromagnetic waves
represents the first ‘multi-messenger’ astronomical observation.
Such observations enable GW170817 to be used as a ‘standard
siren’14–18 (meaning that the absolute distance to the source can be
determined directly from the gravitational-wave measurements)
to measure the Hubble constant. This quantity represents the local
expansion rate of the Universe, sets the overall scale of the Universe
and is of fundamental importance to cosmology. Here we report a
measurement of the Hubble constant that combines the distance
to the source inferred purely from the gravitational-wave signal
with the recession velocity inferred from measurements of the
redshift using the electromagnetic data. In contrast to previous
measurements, ours does not require the use of a cosmic ‘distance
ladder’19: the gravitational-wave analysis can be used to estimate
the luminosity distance out to cosmological scales directly, without
the use of intermediate astronomical distance measurements. We
determine the Hubble constant to be about 70 kilometres per
second per megaparsec. This value is consistent with existing
measurements20,21, while being completely independent of them.
Additional standard siren measurements from future gravitationalwave
sources will enable the Hubble constant to be constrained to
high precision.
Polarized reflected light from the Spica binary systemSérgio Sacani
Close binary systems often show linear polarization varying
over the binary period, usually attributed to light scattered
from electrons in circumstellar clouds1–3
. One of the brightest
close binary systems is Spica (alpha Virginis) consisting of
two B-type stars orbiting with a period of just over four days.
Past observations of Spica have shown low polarization with
no evidence for variability4–6. Here we report new high-precision polarization observations of Spica that show variation
with an amplitude of about 200 parts per million. By including
polarized radiative transfer in a binary star model, we show
that the phase-dependent polarization is mainly due to light
reflected from the primary component of the binary system
off the secondary component and vice versa. The stars reflect
only a few per cent of the incident light, but the reflected light
is very highly polarized. The polarization results show that the
binary orbit is clockwise and the position angle of the line of
nodes is 130.4° ± 6.8°, in agreement with intensity interferometer results7
. We suggest that reflected light polarization
may be much more important in binary systems than has previously been recognized and may be a way of detecting previously unrecognized close binaries.
Convective storms in Europe: a look back at COPS and CSIPAndrew Russell
A seminar given at RMS in London on 16th March on the main results from the Convective Storm Initiation Project (CSIP) and the Convective and Orographically-induced Precipitation Study (COPS).
NRT polarimetry and neutron star mergers - Nam 2019Joseph Fernandez
Talk given in the National Astronomy Meeting 2019, Lancaster, UK.
A large number of neutron star mergers will be detected by LIGO/Virgo in the coming years. GW170817 confirmed that neutron star mergers would actually produce relativistic outflows (e.g. relativistic jets and cocoon). The polarimetry by LT and NRT would enable us to study the properties of the outflow in details (i.e. magnetic field structure/strength, and its angular dependence). We discuss polarization signals in the outflow emission, and we show the expected signal distributions for an upcoming neutron star merger sample.
Flaring from the_supermassive_black_hole_in_mrk335_studied_with_swift_and_nustarSérgio Sacani
Os comportamentos estranhos e desconcertantes dos buracos negros tornam-se cada dia menos misteriosos, com as novas observações feitas com as missões Swift e NuSTAR da NASA. Os dois telescópios espaciais registraram um buraco negro supermassivo no meio de uma gigantesca explosão de luz de raio-X, ajudando os astrônomos a tentarem resolver um grande quebra-cabeça: Como os buracos negros supermassivos emitem flares?
Os resultados sugerem que os buracos negros supermassivos emitem flares de raios-X, quando suas coroas circundantes, fontes de partículas extremamente energéticas, são atiradas ou lançadas para fora dos buracos negros.
“Essa é a primeira vez que nós somos capazes de linkar o lançamento da coroa com uma flare”, disse Dan Wilkins, da Universidade de Saint Mary em Halifax, no Canadá e principal autor do artigo que descreve os resultados na revista Monthly Notices of The Royal Astronomical Society. “Isso nos ajudará a entender como os buracos negros supermassivos alimentam alguns dos objetos mais brilhantes do universo”.
Os buracos negros supermassivos não emitem luz por si só, mas eles as vezes são circundados por discos de material quente e brilhante. A gravidade do buraco negro puxa o gás ao redor, aquecendo esse material e fazendo com que ele brilhe com diferentes tipos de luz. Outra fonte da radiação perto do buraco negro é a coroa. As coroas são feitas de partículas altamente energéticas que geram luz de raio-X, mas os detalhes sobre sua aparência, ou como elas se formam, ainda não são claros.
Multimessenger observations of a flaring blazar coincident with high-energy n...Sérgio Sacani
Neutrinos are tracers of
cosmic-ray acceleration: electrically neutral
and traveling at nearly the speed of light, they
can escape the densest environments and may
be traced back to their source of origin. Highenergy
neutrinos are expected to be produced
in blazars: intense extragalactic radio, optical,
x-ray, and,in some cases, g-ray sources
characterized by relativistic jets of
plasma pointing close to our line of
sight. Blazars are among the most
powerful objects in the Universe and
are widely speculated to be sources
of high-energy cosmic rays. These cosmic
rays generate high-energy neutrinos
and g-rays, which are produced
when the cosmic rays accelerated in
the jet interact with nearby gas or
photons. On 22 September 2017, the
cubic-kilometer IceCube Neutrino
Observatory detected a ~290-TeV
neutrino from a direction consistent
with the flaring g-ray blazar TXS
0506+056. We report the details of
this observation and the results of a
multiwavelength follow-up campaign
An evolucionary missing_link_a_modest_mass_early_type_galaxy_hosting_an_over_...Sérgio Sacani
O buraco negro supermassivo de uma galáxia descoberta recentemente é bem maior do seria possível, de acordo com as atuais teorias da evolução galáctica. Novo trabalho, realizado por astrônomos na Universidade Keele e da Universidade Central Lancashire, mostra que o buraco negro é muito massivo do que deveria ser, se comparado com a massa da galáxia ao redor. Os cientistas publicaram os resultados em um artigo no Monthly Notices of The Royal Astronomical Society.
A galáxia, SAGE0536AGN, foi inicialmente descoberta com o Telescópio Espacial Spitzer da NASA na luz infravermelha. Apesar de ter no mínimo 9 bilhões de anos de vida, ela contém um núcleo galáctico ativo, um AGN, um objeto incrivelmente brilhante resultante da acreção de gás por um buraco negro supermassivo central. O gás é acelerado a altíssimas velocidades devido ao imenso campo gravitacional do buraco negro, fazendo com que o gás emita luz.
A equipe agora também confirmou a presença de um buraco negro medindo a velocidade do gás movendo-se ao seu redor. Usando o Southern African LArge Telescope, os cientistas observaram que uma linha de emissão de hidrogênio, no espectro da galáxia (onde a luz é dispersada em suas diferentes cores – um efeito similar é visto usando um prisma) é alargada pelo Efeito Doppler, onde o comprimento de onda (a cor) da luz de um objeto é desviada para o azul e para o vermelho dependendo se ele está se movendo para perto ou para longe nós. O grau de alargamento implica que o gás está se movendo ao redor numa alta velocidade, um resultado do forte campo gravitacional do buraco negro.
Discovery of rapid whistlers close to Jupiter implying lightning rates simila...Sérgio Sacani
Electrical currents in atmospheric lightning strokes generate
impulsive radio waves in a broad range of frequencies, called
atmospherics. These waves can be modified by their passage
through the plasma environment of a planet into the form of
dispersed whistlers1. In the Io plasma torus around Jupiter,
Voyager 1 detected whistlers as several-seconds-long slowly
falling tones at audible frequencies2. These measurements
were the first evidence of lightning at Jupiter. Subsequently,
Jovian lightning was observed by optical cameras on board
several spacecraft in the form of localized flashes of light3–7.
Here, we show measurements by the Waves instrument8
on board the Juno spacecraft9–11 that indicate observations
of Jovian rapid whistlers: a form of dispersed atmospherics
at extremely short timescales of several milliseconds to
several tens of milliseconds. On the basis of these measurements,
we report over 1,600 lightning detections, the largest
set obtained to date. The data were acquired during close
approaches to Jupiter between August 2016 and September
2017, at radial distances below 5 Jovian radii. We detected up
to four lightning strokes per second, similar to rates in thunderstorms
on Earth12 and six times the peak rates from the
Voyager 1 observations13.
2013 Briefing Update
CLASSIFICATION SCHEME FOR ANTIGRAVITY DEVICES By James E. Cox
It is proposed that the various types of antigravity devices be categorized into the following seven groups:
I. MECHANICAL ANTIGRAVITY DEVICES:
These are purely mechanical devices generally involving high speed rotation and forced precessional features using different materials in some cases. Example members are from Laithwaite, Wallace, Kidd, McCabe, Stratchen, Delroy, Foster, Dean, Forward, dePalma, Hayasaka and Cowlishaw.
II. ACCOUSTICAL ANTIGRAVITY DEVICES:
These devices have no moving parts but employ vibration to alter nuclear interactions with gravity such as the work of Keely, Tibetan's stone levitation, Leedskelstein, and some inventors of acoustical levitation devices.
III. CHARGED STATIC/ROTATING DISC/CONES ANTIGRAVITY:
These are electrostatic/magnetic devices using stationary electrodes at high voltage such as T.T. Brown/Bielfeld and Bahnson, Naudin, Hartman, Nipher, Pages, Kelly, Rieken as well as rotating components such as Searl, Hammel, Davidson, Saxl, Halik, Schauberger, Carr, Hooper, Huaro, Smith and Vril/Schumann.
IV. AC/RF OR MICROWAVE ELECTROMAGNETIC ANTIGRAVITY DEVICES:
In this group are devices with no moving parts having high frequency electromagnetic fields such as Alzofon, Tesla, Littlejohn, Sweet, Nielson, Seike, Hutchinson, Farrow, Bielek, Zinsser, Peshka, Schlecker, and Smith, etc.
V. SOLID STATE ANTIGRAVITY DEVICES:
These devices have their seat of antigravitic/shielding action within the atomic/lattice structure in both steady-state and transient modes such as the BaICuO superconductors used in the Podkletnov and Schnurer devices, (and those who have replicated their effects) as well as excitons in doped crystals.
VI. NUCLEAR ANTIGRAVITATION:
This entails the alteration of the interactions with the nucleus or its modification, to yield a change in weight or generation of gravity beams, or breakdown of Newton's third law such as in the work of Bearden, Wallace, Dan Fry, Gilber Jordan, extraterrestrial spacecraft (Lazar's element 115), Celtan, white powder (monoatomic elements), Dr. Charles Brush, and possibly cold fusion with ZPE interaction.
t
VII. BIOLOGICAL ANTIGRAVITY DEVICES:
These involve the human or animal element to obtain levitation, or weightless, psychokinetic action or inertia modification as in the Dr. William Crookes work on Home, Clark's party levitation, yogi masters, religious saints, Russian mirror chamber research, bumblebee flight as well as the Rhino Beetle.
Copyright Antigravity News and Space Drive Technology
Vol. 2, No. 1, January-February 1998, p. 4.
All Rights Reserved.
Permission is Granted to Copy, Forward, or Post with this Unaltered Notice kept intact.
The AGN Website is at: http://www.padrak.com/agn/
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.
NRT polarimetry and neutron star mergers - Nam 2019Joseph Fernandez
Talk given in the National Astronomy Meeting 2019, Lancaster, UK.
A large number of neutron star mergers will be detected by LIGO/Virgo in the coming years. GW170817 confirmed that neutron star mergers would actually produce relativistic outflows (e.g. relativistic jets and cocoon). The polarimetry by LT and NRT would enable us to study the properties of the outflow in details (i.e. magnetic field structure/strength, and its angular dependence). We discuss polarization signals in the outflow emission, and we show the expected signal distributions for an upcoming neutron star merger sample.
Flaring from the_supermassive_black_hole_in_mrk335_studied_with_swift_and_nustarSérgio Sacani
Os comportamentos estranhos e desconcertantes dos buracos negros tornam-se cada dia menos misteriosos, com as novas observações feitas com as missões Swift e NuSTAR da NASA. Os dois telescópios espaciais registraram um buraco negro supermassivo no meio de uma gigantesca explosão de luz de raio-X, ajudando os astrônomos a tentarem resolver um grande quebra-cabeça: Como os buracos negros supermassivos emitem flares?
Os resultados sugerem que os buracos negros supermassivos emitem flares de raios-X, quando suas coroas circundantes, fontes de partículas extremamente energéticas, são atiradas ou lançadas para fora dos buracos negros.
“Essa é a primeira vez que nós somos capazes de linkar o lançamento da coroa com uma flare”, disse Dan Wilkins, da Universidade de Saint Mary em Halifax, no Canadá e principal autor do artigo que descreve os resultados na revista Monthly Notices of The Royal Astronomical Society. “Isso nos ajudará a entender como os buracos negros supermassivos alimentam alguns dos objetos mais brilhantes do universo”.
Os buracos negros supermassivos não emitem luz por si só, mas eles as vezes são circundados por discos de material quente e brilhante. A gravidade do buraco negro puxa o gás ao redor, aquecendo esse material e fazendo com que ele brilhe com diferentes tipos de luz. Outra fonte da radiação perto do buraco negro é a coroa. As coroas são feitas de partículas altamente energéticas que geram luz de raio-X, mas os detalhes sobre sua aparência, ou como elas se formam, ainda não são claros.
Multimessenger observations of a flaring blazar coincident with high-energy n...Sérgio Sacani
Neutrinos are tracers of
cosmic-ray acceleration: electrically neutral
and traveling at nearly the speed of light, they
can escape the densest environments and may
be traced back to their source of origin. Highenergy
neutrinos are expected to be produced
in blazars: intense extragalactic radio, optical,
x-ray, and,in some cases, g-ray sources
characterized by relativistic jets of
plasma pointing close to our line of
sight. Blazars are among the most
powerful objects in the Universe and
are widely speculated to be sources
of high-energy cosmic rays. These cosmic
rays generate high-energy neutrinos
and g-rays, which are produced
when the cosmic rays accelerated in
the jet interact with nearby gas or
photons. On 22 September 2017, the
cubic-kilometer IceCube Neutrino
Observatory detected a ~290-TeV
neutrino from a direction consistent
with the flaring g-ray blazar TXS
0506+056. We report the details of
this observation and the results of a
multiwavelength follow-up campaign
An evolucionary missing_link_a_modest_mass_early_type_galaxy_hosting_an_over_...Sérgio Sacani
O buraco negro supermassivo de uma galáxia descoberta recentemente é bem maior do seria possível, de acordo com as atuais teorias da evolução galáctica. Novo trabalho, realizado por astrônomos na Universidade Keele e da Universidade Central Lancashire, mostra que o buraco negro é muito massivo do que deveria ser, se comparado com a massa da galáxia ao redor. Os cientistas publicaram os resultados em um artigo no Monthly Notices of The Royal Astronomical Society.
A galáxia, SAGE0536AGN, foi inicialmente descoberta com o Telescópio Espacial Spitzer da NASA na luz infravermelha. Apesar de ter no mínimo 9 bilhões de anos de vida, ela contém um núcleo galáctico ativo, um AGN, um objeto incrivelmente brilhante resultante da acreção de gás por um buraco negro supermassivo central. O gás é acelerado a altíssimas velocidades devido ao imenso campo gravitacional do buraco negro, fazendo com que o gás emita luz.
A equipe agora também confirmou a presença de um buraco negro medindo a velocidade do gás movendo-se ao seu redor. Usando o Southern African LArge Telescope, os cientistas observaram que uma linha de emissão de hidrogênio, no espectro da galáxia (onde a luz é dispersada em suas diferentes cores – um efeito similar é visto usando um prisma) é alargada pelo Efeito Doppler, onde o comprimento de onda (a cor) da luz de um objeto é desviada para o azul e para o vermelho dependendo se ele está se movendo para perto ou para longe nós. O grau de alargamento implica que o gás está se movendo ao redor numa alta velocidade, um resultado do forte campo gravitacional do buraco negro.
Discovery of rapid whistlers close to Jupiter implying lightning rates simila...Sérgio Sacani
Electrical currents in atmospheric lightning strokes generate
impulsive radio waves in a broad range of frequencies, called
atmospherics. These waves can be modified by their passage
through the plasma environment of a planet into the form of
dispersed whistlers1. In the Io plasma torus around Jupiter,
Voyager 1 detected whistlers as several-seconds-long slowly
falling tones at audible frequencies2. These measurements
were the first evidence of lightning at Jupiter. Subsequently,
Jovian lightning was observed by optical cameras on board
several spacecraft in the form of localized flashes of light3–7.
Here, we show measurements by the Waves instrument8
on board the Juno spacecraft9–11 that indicate observations
of Jovian rapid whistlers: a form of dispersed atmospherics
at extremely short timescales of several milliseconds to
several tens of milliseconds. On the basis of these measurements,
we report over 1,600 lightning detections, the largest
set obtained to date. The data were acquired during close
approaches to Jupiter between August 2016 and September
2017, at radial distances below 5 Jovian radii. We detected up
to four lightning strokes per second, similar to rates in thunderstorms
on Earth12 and six times the peak rates from the
Voyager 1 observations13.
2013 Briefing Update
CLASSIFICATION SCHEME FOR ANTIGRAVITY DEVICES By James E. Cox
It is proposed that the various types of antigravity devices be categorized into the following seven groups:
I. MECHANICAL ANTIGRAVITY DEVICES:
These are purely mechanical devices generally involving high speed rotation and forced precessional features using different materials in some cases. Example members are from Laithwaite, Wallace, Kidd, McCabe, Stratchen, Delroy, Foster, Dean, Forward, dePalma, Hayasaka and Cowlishaw.
II. ACCOUSTICAL ANTIGRAVITY DEVICES:
These devices have no moving parts but employ vibration to alter nuclear interactions with gravity such as the work of Keely, Tibetan's stone levitation, Leedskelstein, and some inventors of acoustical levitation devices.
III. CHARGED STATIC/ROTATING DISC/CONES ANTIGRAVITY:
These are electrostatic/magnetic devices using stationary electrodes at high voltage such as T.T. Brown/Bielfeld and Bahnson, Naudin, Hartman, Nipher, Pages, Kelly, Rieken as well as rotating components such as Searl, Hammel, Davidson, Saxl, Halik, Schauberger, Carr, Hooper, Huaro, Smith and Vril/Schumann.
IV. AC/RF OR MICROWAVE ELECTROMAGNETIC ANTIGRAVITY DEVICES:
In this group are devices with no moving parts having high frequency electromagnetic fields such as Alzofon, Tesla, Littlejohn, Sweet, Nielson, Seike, Hutchinson, Farrow, Bielek, Zinsser, Peshka, Schlecker, and Smith, etc.
V. SOLID STATE ANTIGRAVITY DEVICES:
These devices have their seat of antigravitic/shielding action within the atomic/lattice structure in both steady-state and transient modes such as the BaICuO superconductors used in the Podkletnov and Schnurer devices, (and those who have replicated their effects) as well as excitons in doped crystals.
VI. NUCLEAR ANTIGRAVITATION:
This entails the alteration of the interactions with the nucleus or its modification, to yield a change in weight or generation of gravity beams, or breakdown of Newton's third law such as in the work of Bearden, Wallace, Dan Fry, Gilber Jordan, extraterrestrial spacecraft (Lazar's element 115), Celtan, white powder (monoatomic elements), Dr. Charles Brush, and possibly cold fusion with ZPE interaction.
t
VII. BIOLOGICAL ANTIGRAVITY DEVICES:
These involve the human or animal element to obtain levitation, or weightless, psychokinetic action or inertia modification as in the Dr. William Crookes work on Home, Clark's party levitation, yogi masters, religious saints, Russian mirror chamber research, bumblebee flight as well as the Rhino Beetle.
Copyright Antigravity News and Space Drive Technology
Vol. 2, No. 1, January-February 1998, p. 4.
All Rights Reserved.
Permission is Granted to Copy, Forward, or Post with this Unaltered Notice kept intact.
The AGN Website is at: http://www.padrak.com/agn/
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.
A very luminous_magnetar_powered_supernova_associated_with_an_ultra_long_gamm...Sérgio Sacani
Observações obtidas nos Observatórios de La Silla e Paranal no Chile demonstraram pela primeira vez que existe uma ligação entre uma explosão de raios gama de longa duração e uma explosão de supernova de brilho incomum. Os resultados mostram que a supernova não teve origem em decaimento radioativo, como se esperava, mas sim em campos magnéticos muito fortes decaindo em torno de um objeto exótico conhecido como magnetar. Os resultados serão publicados em 9 de julho de 2015 na revista Nature.
As explosões de raios gama constituem um dos eventos associados às maiores explosões que ocorreram desde o Big Bang. São detectadas por telescópios em órbita sensíveis a este tipo de radiação altamente energética, a qual não consegue penetrar a atmosfera terrestre, e são igualmente observadas a maiores comprimentos de onda por outros telescópios, situados tanto no espaço como no solo.
As explosões de raios gama duram tipicamente alguns segundos, mas em casos muito raros podem ocorrer durante horas. Uma destas explosões de longa duração foi captada pelo satélite Swift a 9 de dezembro de 2011 e chamada GRB 111209A. Foi simultaneamente uma das mais longas e mais brilhantes explosões de raios gama jáobservada.
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
Past studies have identified a spatially extended excess of ∼1-3 GeV gamma rays from the region
surrounding the Galactic Center, consistent with the emission expected from annihilating dark
matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics
and origin. By applying cuts to the Fermi event parameter CTBCORE, we suppress the tails
of the point spread function and generate high resolution gamma-ray maps, enabling us to more
easily separate the various gamma-ray components. Within these maps, we find the GeV excess
to be robust and highly statistically significant, with a spectrum, angular distribution, and overall
normalization that is in good agreement with that predicted by simple annihilating dark matter
models. For example, the signal is very well fit by a 36-51 GeV dark matter particle annihilating to
b
¯b with an annihilation cross section of σv = (1−3)×10−26 cm3
/s (normalized to a local dark matter
density of 0.4 GeV/cm3
). Furthermore, we confirm that the angular distribution of the excess is
approximately spherically symmetric and centered around the dynamical center of the Milky Way
(within ∼0.05◦
of Sgr A∗
), showing no sign of elongation along the Galactic Plane. The signal is
observed to extend to at least ' 10◦
from the Galactic Center, disfavoring the possibility that this
emission originates from millisecond pulsars.
An over massive_black_hole_in_a_typical_star_forming_galaxy_2_billion_years_a...Sérgio Sacani
Uma equipe internacional de astrofísicos, liderada por Benny Trakhtenbrot, um pesquiador no Instituto para Astronomia de Zurique ETH, descobriu um gigantesco buraco negro em uma galáxia outrora normal, usando o telescópio Keck I de 10 metros de diâmetro do Observatório W. M. Keck no Havaí. A equipe, conduzindo uma pesquisa rotineira de caça por antigos e massivos buracos negros, foi surpreendida quando encontrou um com uma massa mais de 7 bilhões de vezes a massa do Sol, figurando assim entre os buracos negros mais massivos já descobertos. E pelo fato da galáxia onde ele foi descoberto ser uma galáxia típica em tamanho, o estudo levantou algumas questões sobre as premissas prévias no desenvolvimento das galáxias. As descobertas foram publicadas na revista Science.
Os dados, coletado com o novíssimo instrumento MOSFIRE do observatório Keck, revelou um gigantesco buraco negro na galáxia chamada CID-947 que está a 11 bilhões de anos-luz de distância da Terra. A incrível sensibilidade do MOSFIRE acoplada ao maior telescópio óptico/infravermelho do mundo permitiu que os cientistas pudessem observar e caracterizar esse buraco negro como ele era quando o universo tinha somente 2 bilhões de anos de vida, ou seja, apenas 14% da sua idade atual.
Ainda mais surpreendente que a massa recorde do buraco negro, foi a massa relativamente comum da galáxia que o contém.
A maior parte das galáxias abrigam buracos negros com massas de menos de 1% da massa da galáxia. Na CID 947, a massa do buraco negro é 10% da massa total da galáxia hospedeira. Devido a essa grande disparidade, a equipe deduziu que esse buraco negro cresceu tão rapidamente que a galáxia não foi capaz de pará-lo, levantando assim uma questão sobre o pensamento prévio na co-evolução de galáxias e de seus buracos negros centrais.
A mildly relativistic wide-angle outflow in the neutron-star merger event GW1...Sérgio Sacani
GW170817 was the first gravitational wave detection of a binary
neutron-star merger1
. It was accompanied by radiation across the
electromagnetic spectrum and localized2
to the galaxy NGC 4993
at a distance of 40 megaparsecs. It has been proposed that the
observed γ-ray, X-ray and radio emission is due to an ultrarelativistic
jet launched during the merger, directed away from
our line of sight3–6. The presence of such a jet is predicted from
models that posit neutron-star mergers as the central engines
that drive short hard γ-ray bursts7,8
. Here we report that the radio
light curve of GW170817 has no direct signature of an off-axis
jet afterglow. Although we cannot rule out the existence of a jet
pointing elsewhere, the observed γ-rays could not have originated
from such a jet. Instead, the radio data require a mildly relativistic
wide-angle outflow moving towards us. This outflow could be the
high-velocity tail of the neutron-rich material dynamically ejected
during the merger or a cocoon of material that breaks out when a
jet transfers its energy to the dynamical ejecta. The cocoon model
explains the radio light curve of GW170817 as well as the γ-rays
and X-rays (possibly also ultraviolet and optical emission)9–15, and
is therefore the model most consistent with the observational data.
Cocoons may be a ubiquitous phenomenon produced in neutronstar
mergers, giving rise to a heretofore unidentified population of
radio, ultraviolet, X-ray and γ-ray transients in the local Universe
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)
Forming intracluster gas in a galaxy protocluster at a redshift of 2.16Sérgio Sacani
Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and
pervaded by a diffuse, hot “intracluster medium” (ICM) that dominates the baryonic content of these systems. The formation
and evolution of the ICM across cosmic time1
is thought to be driven by the continuous accretion of matter from the large-scale
filamentary surroundings and dramatic merger events with other clusters or groups. Until now, however, direct observations of
the intracluster gas have been limited only to mature clusters in the latter three-quarters of the history of the Universe, and we
have been lacking a direct view of the hot, thermalized cluster atmosphere at the epoch when the first massive clusters formed.
Here we report the detection (about 6σ) of the thermal Sunyaev-Zeldovich (SZ) effect2
in the direction of a protocluster. In fact,
the SZ signal reveals the ICM thermal energy in a way that is insensitive to cosmological dimming, making it ideal for tracing
the thermal history of cosmic structures3
. This result indicates the presence of a nascent ICM within the Spiderweb protocluster
at redshift z = 2.156, around 10 billion years ago. The amplitude and morphology of the detected signal show that the SZ
effect from the protocluster is lower than expected from dynamical considerations and comparable with that of lower-redshift
group-scale systems, consistent with expectations for a dynamically active progenitor of a local galaxy cluster.
Microwave imaging of quasi-periodic pulsations at flare current sheetSérgio Sacani
Quasi-periodic pulsations (QPPs) are frequently detected in solar and stellar
flares, but the underlying physical mechanisms are still to be ascertained. Here,
we show microwave QPPs during a solar flare originating from quasi-periodic
magnetic reconnection at the flare current sheet. They appear as two vertically
detached but closely related sources with the brighter ones located at flare
loops and the weaker ones along the stretched current sheet. Although the
brightness temperatures of the two microwave sources differ greatly, they
vary in phase with periods of about 10–20 s and 30–60 s. The
gyrosynchrotron-dominated microwave spectra also present a quasi-periodic
soft-hard-soft evolution. These results suggest that relevant high-energy
electrons are accelerated by quasi-periodic reconnection, likely arising from
the modulation of magnetic islands within the current sheet as validated by a
2.5-dimensional magnetohydrodynamic simulation.
PROBING THE SOLAR INTERIOR WITH LENSED GRAVITATIONAL WAVES FROM KNOWN PULSARSSérgio Sacani
When gravitational waves (GWs) from a spinning neutron star arrive from behind the Sun, they are
subjected to gravitational lensing that imprints a frequency-dependent modulation on the waveform.
This modulation traces the projected solar density and gravitational potential along the path as
the Sun passes in front of the neutron star. We calculate how accurately the solar density prole
can be extracted from the lensed GWs using a Fisher analysis. For this purpose, we selected three
promising candidates (the highly spinning pulsars J1022+1001, J1730-2304, and J1745-23) from the
pulsar catalog of the Australia Telescope National Facility. The lensing signature can be measured
with 3 condence when the signal-to-noise ratio (SNR) of the GW detection reaches 100 (f=300Hz)1
over a one-year observation period (where f is the GW frequency). The solar density prole can be
plotted as a function of radius when the SNR improves to & 104.
Resolved imaging confirms a radiation belt around an ultracool dwarfSérgio Sacani
Radiation belts are present in all large-scale Solar System planetary
30 magnetospheres: Earth, Jupiter, Saturn, Uranus, and Neptune1. These persistent
31 equatorial zones of relativistic particles up to tens of MeV in energy can extend farther
32 than 10 times the planet’s radius, emit gradually varying radio emissions2–4 and impact
33 the surface chemistry of close-in moons5. Recent observations demonstrate that very low
34 mass stars and brown dwarfs, collectively known as ultracool dwarfs, can produce planet35
like radio emissions such as periodically bursting aurorae6–8 from large-scale
36 magnetospheric currents9–11. They also exhibit slowly varying quiescent radio
37 emissions7,12,13 hypothesized to trace low-level coronal flaring14,15 despite departing from
38 empirical multi-wavelength flare relationships8,15. Here we present high resolution
39 imaging of the ultracool dwarf LSR J1835+3259 at 8.4 GHz demonstrating that its
40 quiescent radio emission is spatially resolved and traces a double-lobed and axisymmetric
41 structure similar in morphology to the Jovian radiation belts. Up to 18 ultracool dwarf
42 radii separate the two lobes, which are stably present in three observations spanning
43 more than one year. For plasma confined by the magnetic dipole of LSR J1835+3259, we
44 estimate 15 MeV electron energies consistent with Jupiter’s radiation belts4. Our results
45 confirm recent predictions of radiation belts at both ends of the stellar mass sequence8,16–
46 19 and support broader re-examination of rotating magnetic dipoles in producing non47
thermal quiescent radio emissions from brown dwarfs7, fully convective M dwarfs20, and
4
A highly magnetized twin-jet base pinpoints a supermassive black holeSérgio Sacani
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical
models based on (Blandford & Znajek 1977, MNRAS, 179, 433) extract the rotational energy from a Kerr black hole, which could
be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 103 G to 104 G. We imaged the vicinity
of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is
smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the
magnetic field at 1 Schwarzschild radius to lie between 200 G and 8:3 104 G consistent with Blandford & Znajek models.
Similar to The bright optical_flash_and_afterglow_from_the_gamma_ray_burst_grb_130427a (20)
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
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Neuro-symbolic is not enough, we need neuro-*semantic*Frank van Harmelen
Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as “predictable inference”.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
The bright optical_flash_and_afterglow_from_the_gamma_ray_burst_grb_130427a
1. Research Articles
than the typical GRB localized by
Swift. However, even accounting for its
proximity, the intense gamma-ray fluxes observed imply an apparent isotropic
energy release of nearly 1054 ergs and
rank it among the more powerful GRBs
ever detected (3). Subsequent optical
monitoring discovered the emergence
of a broad-line supernova at the GRB
1
1
1
1
1
W. T. Vestrand, * J. A. Wren, A. Panaitescu, P. R. Wozniak, H. Davis, D. M.
location (8).
1
2
2
3
3
4
Palmer, G. Vianello, N. Omodei, S. Xiong, M. S. Briggs, M. Elphick, W.
This powerful GRB also generated
Paciesas,5 W. Rosing4
an extremely bright flash of optical
1
emission and a long-lived, bright, optiLos Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA. 2W.W. Hansen
cal afterglow. Three independent
Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of
Physics, and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA.
RAPTOR (RAPid Telescopes for Opti3
Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman
cal Response) full sky monitoring teleDr., Huntsville, AL 35899, USA. 4Las Cumbres Observatory Global Telescope Network, Inc., 6740 Cortona
scopes (9), at locations in New Mexico
5
Drive, Suite 102, Santa Barbara, CA 93117, USA. Universities Space Research Association, 320
and Hawaii, detected the emergence of
Sparkman Dr., Huntsville, AL 35899, USA.
a bright flash, temporally coincident
*Corresponding author. E-mail: vestrand@lanl.gov
with the onset of gamma-ray emission,
at the location of GRB 130427A. The
The optical light generated simultaneously with x-rays and gamma-rays during a
optical flash rapidly peaked at a magnitude 7.03 ± 0.03 (unfiltered observagamma-ray burst (GRB) provides clues about the nature of the explosions that
occur as massive stars collapse. We report on the bright optical flash and fading
tions calibrated to Sloan r’ band) in an
exposure that covered the time interval
afterglow from powerful burst GRB 130427A. The optical and >100 MeV gamma-ray
flux show a close correlation during the first 7000 s, best explained by reverse
To + 9.31 to To + 19.31 s. After the
shock emission co-generated in the relativistic burst ejecta as it collides with
peak, the flash faded with a power-law
surrounding material. At later times, optical observations show the emergence of
flux decay with index α = –1.67 ± 0.07
emission generated by a forward shock traversing the circumburst environment.
(χ2 = 0.68/5 dof) and was detected for
The link between optical afterglow and >100 MeV emission suggests that nearby
about 80 s until it faded below the
early peaked afterglows will be the best candidates for studying particle
~10th magnitude sensitivity limit of the
acceleration at GeV/TeV energies.
RAPTOR full sky monitors.
The taxonomy for optical emission
detected during the prompt gamma-ray
Long-duration gamma-ray bursts are associated with the collapse of emitting interval identifies two broad classes: prompt optical emission
massive stars to form black holes (1) or rapidly-spinning, highly- correlated with prompt gamma-ray emission (10–12) and early optical
magnetized, neutron stars (2). This collapse is believed to eject collimat- afterglow emission uncorrelated with the prompt gamma-ray emission
ed relativistic jets that, through internal dissipation processes and colli- (11, 13, 14). In context of the standard fireball model (15, 16), the
sions with the surroundings, generate luminous outbursts of prompt optical emission is attributed to internal shocks in an ultraelectromagnetic radiation that have been detected at radio frequencies to relativistic jet outflow generated by the central engine and the afterglow
very high (GeV) gamma-ray energies. Most of the outburst energy is emission to external shocks generated by interaction with the surroundemitted in the gamma-rays. But, starting with the first observations that ing medium. The prompt optical emission therefore reflects the impulestablished that GRBs occur at cosmological distances (3), correlative sive energy injection into the jet and the early afterglow emission
optical observations, in particular, have proven themselves as important measures the response of the jet/environment system to the energy injectools for unraveling the nature of GRB explosions. Here we present ob- tion. Bright optical flashes from reverse shocks were predicted on theoservations of the optical flash and early afterglow for a nearby burst that retical grounds (16, 17) before observational evidence was seen in GRB
is bright enough in very high energy gamma-rays to allow a detailed 990123 (13). The optical flash light-curve for GRB 130427A shows a
comparison of the >100 MeV gamma-ray and optical light curves. These single peak delayed with respect to the keV-MeV prompt gamma-ray
optical observations cover the critical early phases of the explosion from peak (Fig. 1) and a steep power-law flux that is consistent with the prethe time interval before the event onset, through the bright optical and dictions of models for optical flashes from reverse shocks (17). Based on
prompt gamma-ray emitting period, and well into the early afterglow the above taxonomy, the brightness of the flash, and the rapid power law
phase.
flux decay, it makes sense to associate the optical flash with reverse
Starting at 27 April 2013 at 07:47:06.42 UTC (hereafter To), the shock emission.
Gamma Ray Burst Monitor (GBM) on the Fermi Satellite, the Burst
To explore the evolution of the broad band GRB spectrum during the
Alert Telescope (BAT) on the Swift Satellite, and an armada of other optical flash, we constructed spectral energy distributions (SED) using
space-based gamma-ray detectors detected the onset of a powerful gam- simultaneous measurements taken with the Fermi GBM and the Fermi
ma-ray burst (GRB) (4, 5). This GRB, called GRB 130427A, had the Large Area Telescope (LAT). Each snapshot of the time evolving SED
largest gamma-ray fluence (~2.7 × 10–3 erg/cm2 in the 20 keV-1200 keV was formed by integrating the GRB flux over the same time interval as
band) measured in more than 18 years of operation by Konus-Wind (6) the optical exposure. We found that the broad-band SEDs (Fig. 2) varied
and set a record for duration of the >100 MeV gamma-ray emitting in- rapidly during the first 40 s and the optical measurements fell far from
terval (5). Spectroscopy of the optical counterpart (7), coarsely localized the values expected from extrapolation of the keV-MeV SED. However
by the Swift BAT and later refined by follow-up with optical telescopes, as the intensity of the outburst declined during the next 40 s interval, the
places the GRB at a redshift z = 0.34—a distance about five times closer SED shape stabilized and the optical measurements started to converge
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 1 / 10.1126/science.1242316
Downloaded from www.sciencemag.org on December 1, 2013
The Bright Optical Flash and Afterglow
from the Gamma-Ray Burst GRB
130427A
2. on the values predicted by a straightforward linear extrapolation of the
keV-MeV SED. By the end of the optical flash, the optical to 10 MeV
spectrum is consistent with a single power law with index β = –0.64.
In response to the Swift BAT localization alert at 127.8 s after the
GBM trigger, our RAPTOR response telescopes began unfiltered and
simultaneous multicolor (g’, r’, i’, z’) optical observations at To + 132.9
s that continued until To + 7585.9 s. This photometry begins near the
peak of a prominent flare in keV-MeV x-ray/gamma-rays that lasts until
~To +400 s. The optical light curves show a smooth monotonic decline
but no indication of the steep decline nor the break to a slower powerlaw decay at ~400 s measured at x-ray energies (4). Instead, the structure
of the optical light-curve shows a steepening at about To + 270 s. This
steepening is essentially achromatic and the color of the optical emission
is consistent with a ν–0.70 ± 0.05 spectrum and constant until it starts to
become bluer (ν–0.59 ± 0.05) at ~3000 s after the GBM trigger (see bottom
panel of Fig. 3).
In marked contrast with the keV-MeV emission, the optical light
curves after To + 100 s show a striking similarity with the >100 MeV
photon flux light curve measured by the Fermi LAT (5). The LAT light
curve has a break at about 300 s, just like the optical afterglow. Straightforward scaling of the RAPTOR optical light curve by a factor of ~10−6
provides a reasonable description of the LAT observations out to ~To +
7000 s. This close correspondence argues for a common origin of both
components in external shocks.
The optical light curve until ~To + 3000 s is best modeled by synchrotron emission from a reverse shock in a wind density profile. Most
optical afterglows have been modeled with forward shocks in a homogeneous medium. But the peak brightness (~6 Jy) and steep decay of the
optical flash suggest origin in a reverse shock. The relative faintness of
the radio afterglow peak (~1 mJy) also argues for generation by a reverse
shock in a wind-like medium (18). To explain the optical flash by reverse shock emission in a wind (R–2) requires either a long-lived electron
energy injection up to ~40 s or a shorter (~20 s) followed by adiabatic
cooling. Figure 4 shows the best fit to the optical flash with the short
interval of injection (on at To + 4 s and off at To + 20 s) and, for selfconsistency, the same dynamical parameters that we infer from fits to the
later afterglow forward shock emission discussed below. This model
employs an electron distribution with power-law energy index p = 1.88
and corresponds to an injected energy of 8.0 × 1053 ergs. The slower
optical fading after the flash interval requires a second episode of energy
injection to sustain the optical afterglow or a continuous outflow with a
variable Lorentz factor (19). This sustained reverse shock model reproduces the closely tracking variability observed by the RAPTOR telescopes and the Fermi LAT and suggests that the optical and most of the
>100 MeV emission is generated by synchrotron emitting electrons that
are accelerated by the reverse shocks.
This reverse shock model cannot, by itself, explain the properties of
the prompt keV-MeV emission nor some of the properties of the late
time afterglows. The evolution to a bluer color after ~3000 s observed by
RAPTOR and the slowing of the optical brightness decay suggests the
emergence of a forward shock component. This transition to forward
shock dominance at late times would also naturally explain the late time
x-ray light-curve and the sustained >100 MeV emission after 10,000 s.
Emergence of a bluer optical component at late time is similar to the
afterglow evolution of GRB 080319B—another burst with a bright optical flash. For GRB 080319B, the color change was also interpreted as
marking the transition from reverse shock emission dominance to forward shock dominance (12, 20, 21).
During most of the interval before To + 400 s, the keV-MeV xray/gamma-ray emission is consistent with the standard assumption that
the prompt emission is generated by internal shocks in the relativistic jet
ejecta. Our predicted >100 MeV flux from the reverse shock that generates the optical flash is slightly less (~ factor of 2) than the peak meas-
ured by the Fermi LAT (Fig. 4). But the keV-MeV flux is significantly
underpredicted by at least a factor of 10. So the reverse shock in a wind
model requires prompt emission to explain the keV-MeV emission and
might require additional >100 MeV emission to explain the LAT lightcurve peak. In this picture, the keV-MeV light-curve is a proxy that traces the injection of internal jet energy by the central engine. The keVMeV emission therefore indicates two periods of significant energy injection into the jet: the initial 20 s and a period from ~120 to 300 s. The
interesting potential exception to prompt emission dominance in the
keV-MeV range is the period just before onset of the flare at To + 120 s.
During the interval To + 79 s to To + 89 s, the optical afterglow flux
measured by RAPTOR falls right on the extrapolation of the power-law
(index = ~–0.6) measured in the 10 keV-20 MeV energy band by the
GBM. This gamma-ray spectral slope is also similar to spectral slope
that we measure for optical afterglow emission at later times. The
“notch” in the keV-MeV light curve before the flare at To + 120 may be
providing a rare glimpse, similar to that seen in GRB 980923 (22), of
afterglow emission at MeV energies between prompt emission intervals.
The exceptional optical properties observed for the optical flash and
afterglow from GRB 130427A are mostly a result of burst proximity.
The flash peak luminosity for GRB 130427A is among the most powerful events, but its value is consistent with the anti-correlation between
peak time and peak luminosity (Fig. 5) found for optical afterglows (23).
If optical afterglows and >100 MeV gamma-ray afterglows have a common origin, then the peaked optical afterglows that peak early should be
the best candidates for detection at GeV/TeV gamma-ray energies.
References and Notes
1. S. E. Woosley, J. S. Bloom, The supernova gamma-ray burst connection. Annu.
Rev.
Astron.
Astrophys.
44,
507–556
(2006).
doi:10.1146/annurev.astro.43.072103.150558
2. B. D. Metzger, D. Giannios, T. A. Thompson, N. Bucciantini, E. Quataert, The
protomagnetar model for gamma-ray bursts. Mon. Not. R. Astron. Soc. 413,
2031–2056 (2011). doi:10.1111/j.1365-2966.2011.18280.x
3. M. R. Metzger, S. G. Djorgovski, S. R. Kulkarni, C. C. Steidel, K. L.
Adelberger, D. A. Frail, E. Costa, F. Frontera, Spectral constraints on the
redshift of the optical counterpart to the gamma-ray burst of 8 May 1997.
Nature 387, 878 (1997). doi:10.1038/43132
4. A. Maselli, A. Melandri, L. Nava, C. G. Mundell, N. Kawai, S. Campana, S.
Covino, J. R. Cummings, G. Cusumano, P. A. Evans, G. Ghirlanda, G.
Ghisellini, C. Guidorzi, S. Kobayashi, P. Kuin, V. La Parola, V. Mangano, S.
Oates, T. Sakamoto, M. Serino, F. Virgili, B.-B. Zhang, S. Barthelmy, A.
Beardmore, M. G. Bernardini, D. Bersier, D. Burrows, G. Calderone, M.
Capalbi, J. Chiang, P. D’Avanzo, V. D’Elia, M. De Pasquale, D. Fugazza, N.
Gehrels, A. Gomboc, R. Harrison, H. Hanayama, J. Japelj, J. Kennea, D.
Kopac, C. Kouveliotou, D. Kuroda, A. Levan, D. Malesani, F. Marshall, J.
Nousek, P. O’Brien, J. P. Osborne, C. Pagani, K. L. Page, M. Page, M. Perri,
T. Pritchard, P. Romano, Y. Saito, B. Sbarufatti, R. Salvaterra, I. Steele, N.
Tanvir, G. Vianello, B. Weigand, K. Wiersema, Y. Yatsu, T. Yoshii, G.
Tagliaferri, GRB 130427A: A nearby ordinary monster. Science
10.1126/science.1242279 (2013).
5. M. Ackermann, M. Ajello, K. Asano, W. B. Atwood, M. Axelsson, L. Baldini,
J. Ballet, G. Barbiellini, M. G. Baring, D. Bastieri, K. Bechtol, R. Bellazzini,
E. Bissaldi, E. Bonamente, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, J.
Michael Burgess, S. Buson, G. A. Caliandro, R. A. Cameron, P. A. Caraveo,
C. Cecchi, V. Chaplin, E. Charles, A. Chekhtman, C. C. Cheung, J. Chiang,
G. Chiaro, S. Ciprini, R. Claus, W. Cleveland, J. Cohen-Tanugi, A. Collazzi,
L. R. Cominsky, V. Connaughton, J. Conrad, S. Cutini, F. D’Ammando, A.
de Angelis, M. DeKlotz, F. de Palma, C. D. Dermer, R. Desiante, A.
Diekmann, L. Di Venere, P. S. Drell, A. Drlica-Wagner, C. Favuzzi, S. J.
Fegan, E. C. Ferrara, J. Finke, G. Fitzpatrick, W. B. Focke, A. Franckowiak,
Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, N. Gehrels, S. Germani, M.
Gibby, N. Giglietto, M. Giles, F. Giordano, M. Giroletti, G. Godfrey, J.
Granot, I. A. Grenier, J. E. Grove, D. Gruber, S. Guiriec, D. Hadasch, Y.
Hanabata, A. K. Harding, M. Hayashida, E. Hays, D. Horan, R. E. Hughes, Y.
Inoue, T. Jogler, G. Jóhannesson, W. N. Johnson, T. Kawano, J. Knödlseder,
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 2 / 10.1126/science.1242316
3. D. Kocevski, M. Kuss, J. Lande, S. Larsson, L. Latronico, F. Longo, F.
Loparco, M. N. Lovellette, P. Lubrano, M. Mayer, M. N. Mazziotta, J. E.
McEnery, P. F. Michelson, T. Mizuno, A. A. Moiseev, M. E. Monzani, E.
Moretti, A. Morselli, I. V. Moskalenko, S. Murgia, R. Nemmen, E. Nuss, M.
Ohno, T. Ohsugi, A. Okumura, N. Omodei, M. Orienti, D. Paneque, V.
Pelassa, J. S. Perkins, M. Pesce-Rollins, V. Petrosian, F. Piron, G. Pivato, T.
A. Porter, J. L. Racusin, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A.
Reimer, O. Reimer, S. Ritz, M. Roth, F. Ryde, A. Sartori, P. M.
Saz Parkinson, J. D. Scargle, A. Schulz, C. Sgrò, E. J. Siskind, E. Sonbas, G.
Spandre, P. Spinelli, H. Tajima, H. Takahashi, J. G. Thayer, J. B. Thayer, D.
J. Thompson, L. Tibaldo, M. Tinivella, D. F. Torres, G. Tosti, E. Troja, T. L.
Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, B. L. Winer,
K. S. Wood, R. Yamazaki, G. Younes, H.-F. Yu, S. J. Zhu, P. N. Bhat, M. S.
Briggs, D. Byrne, S. Foley, A. Goldstein, P. Jenke, R. M. Kippen, C.
Kouveliotou, S. McBreen, C. Meegan, W. S. Paciesas, R. Preece, A. Rau, D.
Tierney, A. J. van der Horst, A. von Kienlin, C. Wilson-Hodge, S. Xiong, G.
Cusumano, V. La Parola, J. R. Cummings, Fermi-LAT observations of the
gamma-ray burst GRB 130427A. Science 10.1126/science.1242353 (2013).
6. S. Golenetskii et al., “Konus-wind observation of GRB 130427A,” GCN
Circular #14486 (2013).
7. A. J. Levan et al., “GRB 130427A: Gemini-north redshift,” GCN circular
#14455 (2013).
8. D. Xu, A. de Ugarte Postigo, G. Leloudas, T. Krühler, Z. Cano, J. Hjorth, D.
Malesani, J. P. U. Fynbo, C. C. Thöne, R. Sánchez-Ramírez, S. Schulze, P.
Jakobsson, L. Kaper, J. Sollerman, D. J. Watson, A. Cabrera-Lavers, C. Cao,
S. Covino, H. Flores, S. Geier, J. Gorosabel, S. M. Hu, B. Milvang-Jensen, M.
Sparre, L. P. Xin, T. M. Zhang, W. K. Zheng, Y. C. Zou, Discovery of the
broad-lined Type Ic SN 2013cq associated with the very energetic GRB
130427A. Astrophys. J. 776, 98 (2013). doi:10.1088/0004-637X/776/2/98
9. J. Wren, W. T. Vestrand, P. Wozniak, H. Davis, A portable observatory for
persistent monitoring of the night sky. Proc. SPIE 7737, 773723 (2010).
doi:10.1117/12.859039
10. W. T. Vestrand, P. R. Wozniak, J. A. Wren, E. E. Fenimore, T. Sakamoto, R.
R. White, D. Casperson, H. Davis, S. Evans, M. Galassi, K. E. McGowan, J.
A. Schier, J. W. Asa, S. D. Barthelmy, J. R. Cummings, N. Gehrels, D.
Hullinger, H. A. Krimm, C. B. Markwardt, K. McLean, D. Palmer, A.
Parsons, J. Tueller, A link between prompt optical and prompt gamma-ray
emission in gamma-ray bursts. Nature 435, 178–180 (2005). Medline
doi:10.1038/nature03515
11. W. T. Vestrand, J. A. Wren, P. R. Wozniak, R. Aptekar, S. Golentskii, V.
Pal’shin, T. Sakamoto, R. R. White, S. Evans, D. Casperson, E. Fenimore,
Energy input and response from prompt and early optical afterglow emission
in gamma-ray bursts. Nature 442, 172–175 (2006). Medline
doi:10.1038/nature04913
12. J. L. Racusin, S. V. Karpov, M. Sokolowski, J. Granot, X. F. Wu, V. Pal’shin,
S. Covino, A. J. van der Horst, S. R. Oates, P. Schady, R. J. Smith, J.
Cummings, R. L. Starling, L. W. Piotrowski, B. Zhang, P. A. Evans, S. T.
Holland, K. Malek, M. T. Page, L. Vetere, R. Margutti, C. Guidorzi, A. P.
Kamble, P. A. Curran, A. Beardmore, C. Kouveliotou, L. Mankiewicz, A.
Melandri, P. T. O’Brien, K. L. Page, T. Piran, N. R. Tanvir, G. Wrochna, R.
L. Aptekar, S. Barthelmy, C. Bartolini, G. M. Beskin, S. Bondar, M. Bremer,
S. Campana, A. Castro-Tirado, A. Cucchiara, M. Cwiok, P. D’Avanzo, V.
D’Elia, M. D. Valle, A. de Ugarte Postigo, W. Dominik, A. Falcone, F. Fiore,
D. B. Fox, D. D. Frederiks, A. S. Fruchter, D. Fugazza, M. A. Garrett, N.
Gehrels, S. Golenetskii, A. Gomboc, J. Gorosabel, G. Greco, A. Guarnieri, S.
Immler, M. Jelinek, G. Kasprowicz, V. La Parola, A. J. Levan, V. Mangano,
E. P. Mazets, E. Molinari, A. Moretti, K. Nawrocki, P. P. Oleynik, J. P.
Osborne, C. Pagani, S. B. Pandey, Z. Paragi, M. Perri, A. Piccioni, E.
Ramirez-Ruiz, P. W. Roming, I. A. Steele, R. G. Strom, V. Testa, G. Tosti,
M. V. Ulanov, K. Wiersema, R. A. Wijers, J. M. Winters, A. F. Zarnecki, F.
Zerbi, P. Mészáros, G. Chincarini, D. N. Burrows, Broadband observations of
the naked-eye gamma-ray burst GRB 080319B. Nature 455, 183–188 (2008).
Medline doi:10.1038/nature07270
13. C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson,
T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, R. Kehoe, B.
Lee, S. Marshall, T. McKay, R. Miller, L. Piro, W. Priedhorsky, J.
Szymanski, J. Wren, Observations of contemporaneous optical radiation from
a gamma-ray burst. Nature 398, 400–402 (1999). doi:10.1038/18837
14. E. Rykoff, F. Aharonian, C. W. Akerlof, M. C. B. Ashley, S. D. Barthelmy, H.
A. Flewelling, N. Gehrels, E. Göǧüş, T. Güver, Ü. Kiziloǧlu, H. A. Krimm, T.
A. McKay, M. Özel, A. Phillips, R. M. Quimby, G. Rowell, W. Rujopakarn,
B. E. Schaefer, D. A. Smith, W. T. Vestrand, J. C. Wheeler, J. Wren, F. Yuan,
S. A. Yost, Looking into the Fireball: ROTSE-III and Swift observations of
early gamma-ray burst afterglows. Astrophys. J. 702, 489–505 (2009).
doi:10.1088/0004-637X/702/1/489
15. P. Meszaros, M. Rees, Relativistic fireballs and their impact on external
matter—Models for cosmological gamma-ray bursts. Astrophys. J. 405, 278
(1993). doi:10.1086/172360
16. P. Meszaros, M. Rees, Optical and long wavelength afterglow from gammaray bursts. Astrophys. J. 476, 232–237 (1997). doi:10.1086/303625
17. R. Sari, T. Piran, Predictions for the very early afterglow and the optical flash.
Astrophys. J. 520, 641–649 (1999). doi:10.1086/307508
18. T. Laskar, E. Berger, B. A. Zauderer, R. Margutti, A. M. Soderberg, S.
Chakraborti, R. Lunnan, R. Chornock, P. Chandra, A. Ray, A reverse shock in
GRB 130427A. available at http://arxiv.org/abs/1305.2453 (2013).
19. Z. L. Uhm, B. Zhang, R. Hascoët, F. Daigne, R. Mochkovitch, I. H. Park,
Dynamics and afterglow light curves of gamma-ray burst blast waves with a
long-lived reverse shock. Astrophys. J. 761, 147 (2012). doi:10.1088/0004637X/761/2/147
20. P. Wozniak, W. T. Vestrand, A. D. Panaitescu, J. A. Wren, H. R. Davis, R. R.
White, Gamma-Ray burst at the extreme: The naked-eye burst GRB 080319B.
Astrophys. J. 691, 495–502 (2009). doi:10.1088/0004-637X/691/1/495
21. J. S. Bloom, D. A. Perley, W. Li, N. R. Butler, A. A. Miller, D. Kocevski, D.
A. Kann, R. J. Foley, H.-W. Chen, A. V. Filippenko, D. L. Starr, B.
Macomber, J. X. Prochaska, R. Chornock, D. Poznanski, S. Klose, M. F.
Skrutskie, S. Lopez, P. Hall, K. Glazebrook, C. H. Blake, Observations of the
naked-eye GRB 080319B: implications of nature’s brightest explosion.
Astrophys. J. 691, 723–737 (2009). doi:10.1088/0004-637X/691/1/723
22. T. W. Giblin, J. van Paradijs, C. Kouveliotou, V. Connaughton, R. A. M. J.
Wijers, M. S. Briggs, R. D. Preece, G. J. Fishman, Evidence for an early highenergy afterglow observed with BATSE from GRB 980923. Astrophys. J.
524, L47–L50 (1999). doi:10.1086/312285
23. A. Panaitescu, W. T. Vestrand, Taxonomy of gamma-ray burst optical light
curves: Identification of a salient class of early afterglows. Mon. Not. R.
Astron. Soc. 387, 497–504 (2008). doi:10.1111/j.1365-2966.2008.13231.x
24. The RAPTOR optical measurements are available in table S1 of the
supplementary materials on Science Online.
25. R. Blandford, C. McKee, Fluid dynamics of relativistic blast waves. Phys.
Fluids 19, 1130 (1976). doi:10.1063/1.861619
26. E. Bertin, S. Arnouts, SExtractor: Software for source extraction. Astron.
Astrophys. Suppl. Ser. 117, 393–404 (1996). doi:10.1051/aas:1996164
27. E. Hog et al., The Tycho-2 catalogue of the 2.5 million brightest stars. Astron.
Astrophys. 355, L27 (2000).
28. E. Pickles, E. Depagne, All sky spectrally matched UBVRI-ZY and u′g′r′i′z′
magnitudes for stars in the Tycho2 catalog. Publ. Astron. Soc. Pac. 122,
1437–1464 (2010). doi:10.1086/657947
29. C. Ahn, R. Alexandroff, C. Allende Prieto, S. F. Anderson, T. Anderton, B. H.
Andrews, É. Aubourg, S. Bailey, E. Balbinot, R. Barnes, J. Bautista, T. C.
Beers, A. Beifiori, A. A. Berlind, V. Bhardwaj, D. Bizyaev, C. H. Blake, M.
R. Blanton, M. Blomqvist, J. J. Bochanski, A. S. Bolton, A. Borde, J. Bovy,
W. N. Brandt, J. Brinkmann, P. J. Brown, J. R. Brownstein, K. Bundy, N. G.
Busca, W. Carithers, A. R. Carnero, M. A. Carr, D. I. Casetti-Dinescu, Y.
Chen, C. Chiappini, J. Comparat, N. Connolly, J. R. Crepp, S. Cristiani, R. A.
C. Croft, A. J. Cuesta, L. N. da Costa, J. R. A. Davenport, K. S. Dawson, R.
de Putter, N. De Lee, T. Delubac, S. Dhital, A. Ealet, G. L. Ebelke, E. M.
Edmondson, D. J. Eisenstein, S. Escoffier, M. Esposito, M. L. Evans, X. Fan,
B. Femenía Castellá, E. Fernández Alvar, L. D. Ferreira, N. Filiz Ak, H.
Finley, S. W. Fleming, A. Font-Ribera, P. M. Frinchaboy, D. A. GarcíaHernández, A. E. G. Pérez, J. Ge, R. Génova-Santos, B. A. Gillespie, L.
Girardi, J. I. González Hernández, E. K. Grebel, J. E. Gunn, H. Guo, D.
Haggard, J.-C. Hamilton, D. W. Harris, S. L. Hawley, F. R. Hearty, S. Ho, D.
W. Hogg, J. A. Holtzman, K. Honscheid, J. Huehnerhoff, I. I. Ivans, Ž. Ivezić,
H. R. Jacobson, L. Jiang, J. Johansson, J. A. Johnson, G. Kauffmann, D.
Kirkby, J. A. Kirkpatrick, M. A. Klaene, G. R. Knapp, J.-P. Kneib, J.-M. Le
Goff, A. Leauthaud, K.-G. Lee, Y. S. Lee, D. C. Long, C. P. Loomis, S.
Lucatello, B. Lundgren, R. H. Lupton, B. Ma, Z. Ma, N. MacDonald, C. E.
Mack, S. Mahadevan, M. A. G. Maia, S. R. Majewski, M. Makler, E.
Malanushenko, V. Malanushenko, A. Manchado, R. Mandelbaum, M.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 3 / 10.1126/science.1242316
4. Manera, C. Maraston, D. Margala, S. L. Martell, C. K. McBride, I. D.
McGreer, R. G. McMahon, B. Ménard, S. Meszaros, J. Miralda-Escudé, A. D.
Montero-Dorta, F. Montesano, H. L. Morrison, D. Muna, J. A. Munn, H.
Murayama, A. D. Myers, A. F. Neto, D. C. Nguyen, R. C. Nichol, D. L.
Nidever, P. Noterdaeme, S. E. Nuza, R. L. C. Ogando, M. D. Olmstead, D. J.
Oravetz, R. Owen, N. Padmanabhan, N. Palanque-Delabrouille, K. Pan, J. K.
Parejko, P. Parihar, I. Pâris, P. Pattarakijwanich, J. Pepper, W. J. Percival, I.
Pérez-Fournon, I. Pérez-Ràfols, P. Petitjean, J. Pforr, M. M. Pieri, M. H.
Pinsonneault, G. F. Porto de Mello, F. Prada, A. M. Price-Whelan, M. J.
Raddick, R. Rebolo, J. Rich, G. T. Richards, A. C. Robin, H. J. Rocha-Pinto,
C. M. Rockosi, N. A. Roe, A. J. Ross, N. P. Ross, G. Rossi, J. A. RubiñoMartin, L. Samushia, J. Sanchez Almeida, A. G. Sánchez, B. Santiago, C.
Sayres, D. J. Schlegel, K. J. Schlesinger, S. J. Schmidt, D. P. Schneider, M.
Schultheis, A. D. Schwope, C. G. Scóccola, U. Seljak, E. Sheldon, Y. Shen,
Y. Shu, J. Simmerer, A. E. Simmons, R. A. Skibba, M. F. Skrutskie, A.
Slosar, F. Sobreira, J. S. Sobeck, K. G. Stassun, O. Steele, M. Steinmetz, M.
A. Strauss, A. Streblyanska, N. Suzuki, M. E. C. Swanson, T. Tal, A. R.
Thakar, D. Thomas, B. A. Thompson, J. L. Tinker, R. Tojeiro, C. A.
Tremonti, M. Vargas Magaña, L. Verde, M. Viel, S. K. Vikas, N. P. Vogt, D.
A. Wake, J. Wang, B. A. Weaver, D. H. Weinberg, B. J. Weiner, A. A. West,
M. White, J. C. Wilson, J. P. Wisniewski, W. M. Wood-Vasey, B. Yanny, C.
Yèche, D. G. York, O. Zamora, G. Zasowski, I. Zehavi, G.-B. Zhao, Z.
Zheng, G. Zhu, J. C. Zinn, The ninth data release of the Sloan Digital Sky
Survey: First spectroscopic data from the SDSS-III Baryon Oscillation
Spectroscopic Survey. Astrophys. J. Suppl. Ser. 203, 21 (2012).
doi:10.1088/0067-0049/203/2/21
30. Y. C. Pei, Interstellar dust from the Milky Way to the Magellanic Clouds.
Astrophys. J. 395, 130 (1992). doi:10.1086/171637
31. D. J. Schlegel, D. P. Finkbeiner, M. Davis, Maps of dust infrared emission for
use in estimation of reddening and cosmic microwave background radiation
foregrounds. Astrophys. J. 500, 525–553 (1998). doi:10.1086/305772
Acknowledgments: This gamma-ray burst research was supported by NASA and
the Laboratory Directed Research and Development program at Los Alamos
National Laboratory. The optical measurements reported in this paper are
available online in the supplementary materials.
Supplementary Materials
www.sciencemag.org/cgi/content/full/science.1242316/DC1
Supplementary Text
Table S1
References (25–31)
24 June 2013; accepted 21 October 2013
Published online 21 November 2013
10.1126/science.1242316
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 4 / 10.1126/science.1242316
5. Fig. 1. A comparison of the relative flux variations measured for GRB 130427A by the Fermi LAT, RAPTOR, and the
Swift BAT during the first 90 s after the gamma-ray burst trigger. The >100 MeV emission and the 50-150 keV emission
have been integrated over the same time intervals as the optical exposures and multiplied by a scaling factor to allow
comparison with the optical light curve. Both the optical and >100 MeV light curves rise to a peak in the second interval, 50-150
keV emission peaks in the first interval.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 5 / 10.1126/science.1242316
6. Fig. 2. The spectral energy distributions measured for GRB 130427A during the early phases of the burst
development. The points and solid lines represent actual measurements. The dotted straight lines indicate the extrapolation
the keV-MeV measurements for comparison to the optical measurements. The dashed lines indicate the connection between
energy bands and are not actual measurements. The measurements were obtained by RAPTOR, the Fermi GBM, and the
Fermi LAT. The errors bars on the GBM measurements have been increased by 25% to allow for systematics, such as pulse
pile-up (PPU), background subtraction during and following the repointing of Fermi, and the rapid spectral evolution during the
exposure intervals.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 6 / 10.1126/science.1242316
7. Fig. 3. Simultaneous multi-color measurements of the
early optical afterglow from GRB 130427A. The top panel
shows the light-curves obtained using standard Sloan g’, r’,
i’, z’ filters (24). The light-curves show more structure than is
captured by power law fits. But the r’ band light-curve can be
characterized as a power-law decay with index ~0.7 before
270 s, ~1.1 between 270 and 3000 s, and 0.88 between
3000 and 7500 s. Also plotted for comparison, in blue, is the
photon flux light curve for >100 MeV emission measured by
the Fermi LAT (4). The bottom panel shows the g’-r’ color
evolution of GRB 130427A. The red line indicates the mean
g’-r’ value (0.286 ± 0.018) measured before T0 + 1000 s.
After about T0 + 3000 s a bluer component emerges as the
flux decay slows.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 7 / 10.1126/science.1242316
8. Fig. 4. Best-fit with a reverse-forward shock model to the optical light-curve of GRB afterglow 130427A. Three
episodes of ejecta and energy injection are needed to explain the optical flash, the early optical emission (up to few ks), and
the late optical emission (after a few ks). Here each “injection episode” represents a change in the dynamical and microphysical parameters of the reverse shock in an otherwise continuous ejecta injection into the reverse-shock. For the first two
52
episodes, the optical emission arises from the reverse shock, and the kinetic energy of the incoming ejecta (6.10 erg/sr and
53
54
4.10 erg/sr, respectively) is less than that of the leading shock (10 erg/sr). During the last injection episode, the optical
54
afterglow emission arises from the forward-shock, with the incoming ejecta carrying 3.10 erg/sr, which is more than that
already existing in the forward-shock (thus its deceleration is mitigated by the energy injection). Other parameters are: 1) first
injection episode, flash reverse-shock (fRS)–onset at 4 s, end at 15 s, incoming ejecta Lorentz factor 730, magnetic field
parameter 0.008, electron energy parameter 0.006, index of electron power-law distribution with energy 1.9 2) second injection
episode, reverse-shock (RS, parameters in same order as above)–15 s, 3 ks, 1800, 0.0010, 0.012, 2.0. 3) third injection
−4
0.3
episode, forward-shock (FS)–3 ks, > 2 Ms, > 100, 3.10 , 0.14, 2.3, energy injection law E ~ t . The micro-physical
parameters for the forward shock are kept constant throughout the entire course of the event. We also require that the ambient
–2
medium have a wind-like density stratification (n ~ r ) corresponding to a GRB progenitor with a mass-loss rate–to–wind
−11
speed ratio of 4.10 (M_sun/yr)/(km/s). Dot-dash lines show the model fits for the flash phase emission, the solid lines show
the reverse shock contributions during the early afterglow phase, and the dashed lines shows the contributions of the forward
shock emission to the late optical afterglow and all phases of the x-ray afterglow. The reverse-shock emission during the third
injection episode is not shown and would be dimmer than that of the forward-shock, if the reverse-shock has the same microphysical parameters as the forward-shock.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 8 / 10.1126/science.1242316
9. Fig. 5. A comparison of the light-curve from GRB
130427A (in green) with those measured for other
prominent GRBs with peaked optical afterglows. All of
the light-curves have been transformed to show how they
would appear if they had occurred at redshift z = 2.
/ http://www.sciencemag.org/content/early/recent / 21 November 2013 / Page 9 / 10.1126/science.1242316