SunPy: A Python package for Solar Physics
@article{ 2020JOSS....5.1832M,
title = { SunPy: A Python package for Solar Physics },
journal = { The Journal of Open Source Software },
year = { 2020 },
month = { February },
volume = { 5 },
number = { 46 },
pages = { 1832 },
doi = { 10.21105/joss.01832 },
}
A Precessing Numerical Relativity Waveform Surrogate Model for Binary Black Holes: A Gaussian Process Regression Approach
Gravitational wave astrophysics relies heavily on the use of matched filtering both to detect signals in noisy data from detectors, and to perform parameter estimation on those signals. Matched filtering relies upon prior knowledge of the signals expected to be produced by a range of astrophysical systems, such as binary black holes. These waveform signals can be computed using numerical relativity techniques, where the Einstein field equations are solved numerically, and the signal is extracted from the simulation. Numerical relativity simulations are, however, computationally expensive, leading to the need for a surrogate model which can predict waveform signals in regions of the physical parameter space which have not been probed directly by simulation. We present a method for producing such a surrogate using Gaussian process regression which is trained directly on waveforms generated by numerical relativity. This model returns not just a single interpolated value for the waveform at a new point, but a full posterior probability distribution on the predicted value. This model is therefore an ideal component in a Bayesian analysis framework, through which the uncertainty in the interpolation can be taken into account when performing parameter estimation of signals.
@article{ 2019arXiv190309204W,
author = { Williams, D } and { Heng, IS } and { Gair, J } and { Clark, JA } and { Khamesra, B },
title = { A Precessing Numerical Relativity Waveform Surrogate Model for Binary Black Holes: A Gaussian Process Regression Approach },
journal = { Physical Review D },
year = { 2020 },
volume = { 101 },
doi = { 10.1103/PhysRevD.101.063011 },
}
Comparing Short GammaRay Burst Jet Structure Models
A structured gammaray burst jet could explain the dimness of the prompt emission observed from GRB170817A but the exact form of this structure is still ambiguous. However, with the promise of future joint gravitational wave and gammaray burst observations, we shall be able to examine populations of binary neutron star mergers rather than a casebycase basis. We present an analysis that considers gravitational wave triggered binary neutron star events both with and without short gammaray burst counterparts assuming that events without a counterpart were observed offaxis. This allows for Bayes factors to be calculated to compare different jet structure models. We perform model comparison between a Gaussian and powerlaw apparent jet structure on simulated data to demonstrate that the correct model can be distinguished with a log Bayes factor of >5 after less than 100 events. Constraints on the apparent structure jet model parameters are also made. After 25(100) events the angular width of the core of a powerlaw jet structure can be constrained within a 90% credible interval of width ∼9.1(4.4)∘, and the outer beaming angle to be within ∼19.9(8.5)∘. Similarly we show the width of a Gaussian jet structure to be constrained to ∼2.8(1.6)∘.
@article{ 2020ApJ...891..124H,
author = { Hayes, F } and { Heng, IS } and { Veitch, J } and { Williams, D },
title = { Comparing Short GammaRay Burst Jet Structure Models },
journal = { Astrophysical Journal },
year = { 2020 },
month = { mar },
volume = { 891 },
number = { 2 },
pages = { 124 },
doi = { 10.3847/15384357/ab72fc },
}
Search for Multimessenger Sources of Gravitational Waves and Highenergy Neutrinos with Advanced LIGO during Its First Observing Run, ANTARES, and IceCube
{Astrophysical sources of gravitational waves, such as binary neutron
star and black hole mergers or corecollapse supernovae, can
drive relativistic outflows, giving rise to nonthermal high
energy emission. Highenergy neutrinos are signatures of such
outflows. The detection of gravitational waves and highenergy
neutrinos from common sources could help establish the
connection between the dynamics of the progenitor and the
properties of the outflow. We searched for associated emission
of gravitational waves and highenergy neutrinos from
astrophysical transients with minimal assumptions using data
from Advanced LIGO from its first observing run O1, and data
from the ANTARES and IceCube neutrino observatories from the
same time period. We focused on candidate events whose
astrophysical origins could not be determined from a single
messenger. We found no significant coincident candidate, which
we used to constrain the rate density of astrophysical sources
dependent on their gravitationalwave and neutrino emission
processes.}
@article{ 2019ApJ...870..134A,
title = { Search for Multimessenger Sources of Gravitational Waves and Highenergy Neutrinos with Advanced LIGO during Its First Observing Run, ANTARES, and IceCube },
journal = { Astrophysical Journal },
year = { 2019 },
month = { January },
volume = { 870 },
number = { 2 },
pages = { 134 },
doi = { 10.3847/15384357/aaf21d },
}
A Fermi GammaRay Burst Monitor Search for Electromagnetic Signals Coincident with Gravitationalwave Candidates in Advanced LIGO's First Observing Run
{We present a search for prompt gammaray counterparts to compact binary
coalescence gravitational wave (GW) candidates from Advanced
LIGO{\textquoteright}s first observing run (O1). As demonstrated
by the multimessenger observations of GW170817/GRB 170817A,
electromagnetic and GW observations provide complementary
information about the astrophysical source, and in the case of
weaker candidates, may strengthen the case for an astrophysical
origin. Here we investigate lowsignificance GW candidates from
the O1 compact binary coalescence searches using the Fermi
GammaRay Burst Monitor (GBM), leveraging its all sky and broad
energy coverage. Candidates are ranked and compared to
background to measure the significance. Those with false alarm
rates (FARs) of less than 10$^{5}$ Hz (about one per day,
yielding a total of 81 candidates) are used as the search sample
for gammaray followup. No GW candidates were found to be
coincident with gammaray transients independently identified by
blind searches of the GBM data. In addition, GW candidate event
times were followed up by a separate targeted search of GBM
data. Among the resulting GBM events, the two with the lowest
FARs were the gammaray transient GW150914GBM presented in
Connaughton et al. and a solar flare in chance coincidence with
a GW candidate.}
@article{ 2019ApJ...871...90B,
title = { A Fermi GammaRay Burst Monitor Search for Electromagnetic Signals Coincident with Gravitationalwave Candidates in Advanced LIGO's First Observing Run },
journal = { Astrophysical Journal },
year = { 2019 },
month = { January },
volume = { 871 },
number = { 1 },
pages = { 90 },
doi = { 10.3847/15384357/aaf726 },
}
Properties of the Binary Neutron Star Merger GW170817
{On August 17, 2017, the Advanced LIGO and Advanced Virgo gravitational
wave detectors observed a lowmass compact binary inspiral. The
initial sky localization of the source of the gravitationalwave
signal, GW170817, allowed electromagnetic observatories to
identify NGC 4993 as the host galaxy. In this work, we improve
initial estimates of the binary's properties, including
component masses, spins, and tidal parameters, using the known
source location, improved modeling, and recalibrated Virgo data.
We extend the range of gravitationalwave frequencies considered
down to 23 Hz, compared to 30 Hz in the initial analysis. We
also compare results inferred using several signal models, which
are more accurate and incorporate additional physical effects as
compared to the initial analysis. We improve the localization of
the gravitationalwave source to a 90\% credible region of 16
deg$^{2}$ . We find tighter constraints on the masses, spins,
and tidal parameters, and continue to find no evidence for
nonzero component spins. The component masses are inferred to
lie between 1.00 and 1.89 M$_{☉}$ when allowing for large
component spins, and to lie between 1.16 and 1.60 M$_{☉}$ (with
a total mass 2.73$_{0.01}$$^{+0.04}$ M$_{☉}$ ) when the spins
are restricted to be within the range observed in Galactic
binary neutron stars. Using a precessing model and allowing for
large component spins, we constrain the dimensionless spins of
the components to be less than 0.50 for the primary and 0.61 for
the secondary. Under minimal assumptions about the nature of the
compact objects, our constraints for the tidal deformability
parameter {\ensuremath{\Lambda}} ̃ are (0,630) when we allow for
large component spins, and 300$_{230}$$^{+420}$ (using a 90\%
highest posterior density interval) when restricting the
magnitude of the component spins, ruling out several equation
ofstate models at the 90\% credible level. Finally, with LIGO
and GEO600 data, we use a Bayesian analysis to place upper
limits on the amplitude and spectral energy density of a
possible postmerger signal.
}
@article{ 2019PhRvX...9a1001A,
title = { Properties of the Binary Neutron Star Merger GW170817 },
journal = { Physical Review X },
year = { 2019 },
month = { January },
volume = { 9 },
number = { 1 },
pages = { 011001 },
doi = { 10.1103/PhysRevX.9.011001 },
}
Constraining the p Modeg Mode Tidal Instability with GW170817
{We analyze the impact of a proposed tidal instability coupling p modes
and g modes within neutron stars on GW170817. This nonresonant
instability transfers energy from the orbit of the binary to
internal modes of the stars, accelerating the gravitationalwave
driven inspiral. We model the impact of this instability on the
phasing of the gravitational wave signal using three parameters
per star: an overall amplitude, a saturation frequency, and a
spectral index. Incorporating these additional parameters, we
compute the Bayes factor (ln B$_{!p}$$^{g p g}$ ) comparing our
p g model to a standard one. We find that the observed signal
is consistent with waveform models that neglect p g effects,
with ln B$_{!p}$$^{g p g}$ =0.0 3$_{0.58}$$^{+0.70}$ (maximum a
posteriori and 90\% credible region). By injecting simulated
signals that do not include p g effects and recovering them
with the p g model, we show that there is a ≃50 \% probability
of obtaining similar ln B$_{!p}$$^{g p g}$ even when p g
effects are absent. We find that the p g amplitude for 1.4
M$_{☉}$ neutron stars is constrained to less than a few tenths
of the theoretical maximum, with maxima a posteriori near one
tenth this maximum and p g saturation frequency ̃70 Hz . This
suggests that there are less than a few hundred excited modes,
assuming they all saturate by wave breaking. For comparison,
theoretical upper bounds suggest
{\ensuremath{\lesssim}}{}10$^{3}$ modes saturate by wave
breaking. Thus, the measured constraints only rule out extreme
values of the p g parameters. They also imply that the
instability dissipates {\ensuremath{\lesssim}}1 {}0$^{51}$ erg
over the entire inspiral, i.e., less than a few percent of the
energy radiated as gravitational waves.
}
@article{ 2019PhRvL.122f1104A,
title = { Constraining the p Modeg Mode Tidal Instability with GW170817 },
journal = { Physical Review Letters },
year = { 2019 },
month = { February },
volume = { 122 },
number = { 6 },
pages = { 061104 },
doi = { 10.1103/PhysRevLett.122.061104 },
}
Search for Transient Gravitationalwave Signals Associated with Magnetar Bursts during Advanced LIGO's Second Observing Run
{We present the results of a search for short and intermediateduration
gravitationalwave signals from four magnetar bursts in Advanced
LIGO{\textquoteright}s second observing run. We find no evidence
of a signal and set upper bounds on the root sum squared of the
total dimensionless strain (h $_{rss}$) from incoming
intermediateduration gravitational waves ranging from 1.1
{\texttimes} 10$^{22}$ at 150 Hz to 4.4 {\texttimes} 10$^{22}$
at 1550 Hz at 50\% detection efficiency. From the known distance
to the magnetar SGR 180620 (8.7 kpc), we can place upper bounds
on the isotropic gravitationalwave energy of 3.4 {\texttimes}
{}10$^{44}$ erg at 150 Hz assuming optimal orientation. This
represents an improvement of about a factor of 10 in strain
sensitivity from the previous search for such signals, conducted
during initial LIGO{\textquoteright}s sixth science run. The
shortduration search yielded upper limits of 2.1 {\texttimes}
{}10$^{44}$ erg for short white noise bursts, and 2.3
{\texttimes} {}10$^{47}$ erg for 100 ms long ringdowns at 1500
Hz, both at 50\% detection efficiency.}
@article{ 2019ApJ...874..163A,
title = { Search for Transient Gravitationalwave Signals Associated with Magnetar Bursts during Advanced LIGO's Second Observing Run },
journal = { Astrophysical Journal },
year = { 2019 },
month = { April },
volume = { 874 },
number = { 2 },
pages = { 163 },
doi = { 10.3847/15384357/ab0e15 },
}
Searches for Continuous Gravitational Waves from 15 Supernova Remnants and Fomalhaut b with Advanced LIGO
{We describe directed searches for continuous gravitational waves (GWs)
from 16 welllocalized candidate neutron stars, assuming none of
the stars has a binary companion. The searches were directed
toward 15 supernova remnants and Fomalhaut b, a directly imaged
extrasolar planet candidate that has been suggested to be a
nearby old neutron star. Each search covered a broad band of
frequencies and first and second time derivatives. After
coherently integrating spans of data from the first Advanced
LIGO observing run of 3.553.7 days per search, applying data
based vetoes, and discounting known instrumental artifacts, we
found no astrophysical signals. We set upper limits on intrinsic
GW strain as strict as 1 {\texttimes} 10$^{25}$, fiducial
neutron star ellipticity as strict as 2 {\texttimes} 10$^{9}$,
and fiducial rmode amplitude as strict as 3 {\texttimes}
10$^{8}$.
Any correspondence should be addressed to and .}
@article{ 2019ApJ...875..122A,
title = { Searches for Continuous Gravitational Waves from 15 Supernova Remnants and Fomalhaut b with Advanced LIGO },
journal = { Astrophysical Journal },
year = { 2019 },
month = { April },
volume = { 875 },
number = { 2 },
pages = { 122 },
doi = { 10.3847/15384357/ab113b },
}
Search for Gravitational Waves from a Longlived Remnant of the Binary Neutron Star Merger GW170817
{One unanswered question about the binary neutron star coalescence
GW170817 is the nature of its postmerger remnant. A previous
search for postmerger gravitational waves targeted high
frequency signals from a possible neutron star remnant with a
maximum signal duration of 500 s. Here, we revisit the neutron
star remnant scenario and focus on longer signal durations, up
until the end of the second Advanced LIGOVirgo observing run,
which was 8.5 days after the coalescence of GW170817. The main
physical scenario for this emission is the powerlaw spindown of
a massive magnetarlike remnant. We use four independent search
algorithms with varying degrees of restrictiveness on the signal
waveform and different ways of dealing with noise artefacts. In
agreement with theoretical estimates, we find no significant
signal candidates. Through simulated signals, we quantify that
with the current detector sensitivity, nowhere in the studied
parameter space are we sensitive to a signal from more than 1
Mpc away, compared to the actual distance of 40 Mpc. However,
this study serves as a prototype for postmerger analyses in
future observing runs with expected higher sensitivity.}
@article{ 2019ApJ...875..160A,
title = { Search for Gravitational Waves from a Longlived Remnant of the Binary Neutron Star Merger GW170817 },
journal = { Astrophysical Journal },
year = { 2019 },
month = { April },
volume = { 875 },
number = { 2 },
pages = { 160 },
doi = { 10.3847/15384357/ab0f3d },
}
Lowlatency Gravitationalwave Alerts for Multimessenger Astronomy during the Second Advanced LIGO and Virgo Observing Run
{Advanced LIGO{\textquoteright}s second observing run (O2), conducted
from 2016 November 30 to 2017 August 25, combined with Advanced
Virgo{\textquoteright}s first observations in 2017 August,
witnessed the birth of gravitationalwave multimessenger
astronomy. The first ever gravitationalwave detection from the
coalescence of two neutron stars, GW170817, and its gammaray
counterpart, GRB 170817A, led to an electromagnetic followup of
the event at an unprecedented scale. Several teams from across
the world searched for EM/neutrino counterparts to GW170817,
paving the way for the discovery of optical, Xray, and radio
counterparts. In this article, we describe the online
identification of gravitationalwave transients and the
distribution of gravitationalwave alerts by the LIGO and Virgo
collaborations during O2. We also describe the gravitational
wave observables that were sent in the alerts to enable searches
for their counterparts. Finally, we give an overview of the
online candidate alerts shared with observing partners during
O2. Alerts were issued for 14 candidates, 6 of which have been
confirmed as gravitationalwave events associated with the
merger of black holes or neutron stars. Of the 14 alerts, 8 were
issued less than an hour after data acquisition.}
@article{ 2019ApJ...875..161A,
title = { Lowlatency Gravitationalwave Alerts for Multimessenger Astronomy during the Second Advanced LIGO and Virgo Observing Run },
journal = { Astrophysical Journal },
year = { 2019 },
month = { April },
volume = { 875 },
number = { 2 },
pages = { 161 },
doi = { 10.3847/15384357/ab0e8f },
}
Allsky search for longduration gravitationalwave transients in the second Advanced LIGO observing run
{We present the results of a search for longduration gravitationalwave
transients in the data from the Advanced LIGO second observation
run; we search for gravitationalwave transients of 2500 s
duration in the 242048 Hz frequency band with minimal
assumptions about signal properties such as waveform
morphologies, polarization, sky location or time of occurrence.
Signal families covered by these search algorithms include
fallback accretion onto neutron stars, broadband chirps from
innermost stable circular orbit waves around rotating black
holes, eccentric inspiralmergerringdown compact binary
coalescence waveforms, and other models. The second observation
run totals about 118.3 days of coincident data between November
2016 and August 2017. We find no significant events within the
parameter space that we searched, apart from the already
reported binary neutron star merger GW170817. We thus report
sensitivity limits on the rootsumsquare strain amplitude
h$_{rss}$ at 50\% efficiency. These sensitivity estimates are an
improvement relative to the first observing run and also done
with an enlarged set of gravitationalwave transient waveforms.
Overall, the best search sensitivity is h$_{rss}$$^{50 \%}$=2.7
{\texttimes}10$^{22}$ Hz$^{1 /2}$ for a millisecond magnetar
model. For eccentric compact binary coalescence signals, the
search sensitivity reaches h$_{rss}$$^{50 \%}$=9.6
{\texttimes}10$^{22}$ Hz$^{1 /2}$ .
}
@article{ 2019PhRvD..99j4033A,
title = { Allsky search for longduration gravitationalwave transients in the second Advanced LIGO observing run },
journal = { Physical Review D },
year = { 2019 },
month = { May },
volume = { 99 },
number = { 10 },
pages = { 104033 },
doi = { 10.1103/PhysRevD.99.104033 },
}
Narrowband search for gravitational waves from known pulsars using the second LIGO observing run
{Isolated spinning neutron stars, asymmetric with respect to their
rotation axis, are expected to be sources of continuous
gravitational waves. The most sensitive searches for these
sources are based on accurate matched filtering techniques that
assume the continuous wave to be phase locked with the pulsar
beamed emission. While matched filtering maximizes the search
sensitivity, a significant signaltonoise ratio loss will
happen in the case of a mismatch between the assumed and the
true signal phase evolution. Narrowband algorithms allow for a
small mismatch in the frequency and spindown values of the
pulsar while coherently integrating the entire dataset. In this
paper, we describe a narrowband search using LIGO O2 data for
the continuous wave emission of 33 pulsars. No evidence of a
continuous wave signal is found, and upper limits on the
gravitational wave amplitude over the analyzed frequency and
spindown ranges are computed for each of the targets. In this
search, we surpass the spindown limit, namely, the maximum
rotational energy loss due to gravitational waves emission for
some of the pulsars already present in the LIGO O1 narrowband
search, such as J 1400 6325 , J 1813 1246 , J 1833 1034 , J
1952 +3252 , and for new targets such as J 0940 5428 and J 1747
2809 . For J 1400 6325 , J 1833 1034 , and J 1747 2809 ,
this is the first time the spindown limit is surpassed.}
@article{ 2019PhRvD..99l2002A,
title = { Narrowband search for gravitational waves from known pulsars using the second LIGO observing run },
journal = { Physical Review D },
year = { 2019 },
month = { June },
volume = { 99 },
number = { 12 },
pages = { 122002 },
doi = { 10.1103/PhysRevD.99.122002 },
}
Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 20152017 LIGO Data
{We present a search for gravitational waves from 222 pulsars with
rotation frequencies {\ensuremath{\gtrsim}}10 Hz. We use
advanced LIGO data from its first and second observing runs
spanning 20152017, which provides the highestsensitivity
gravitationalwave data so far obtained. In this search we
target emission from both the l = m = 2 mass quadrupole mode,
with a frequency at twice that of the pulsar{\textquoteright}s
rotation, and the l = 2, m = 1 mode, with a frequency at the
pulsar rotation frequency. The search finds no evidence for
gravitationalwave emission from any pulsar at either frequency.
For the l = m = 2 mode search, we provide updated upper limits
on the gravitationalwave amplitude, mass quadrupole moment, and
fiducial ellipticity for 167 pulsars, and the first such limits
for a further 55. For 20 young pulsars these results give limits
that are below those inferred from the pulsars{\textquoteright}
spindown. For the Crab and Vela pulsars our results constrain
gravitationalwave emission to account for less than 0.017\% and
0.18\% of the spindown luminosity, respectively. For the
recycled millisecond pulsar J07116830 our limits are only a
factor of 1.3 above the spindown limit, assuming the canonical
value of {}10$^{38}$ kg m$^{2}$ for the star{\textquoteright}s
moment of inertia, and imply a gravitationalwavederived upper
limit on the star{\textquoteright}s ellipticity of 1.2
{\texttimes} 10$^{8}$. We also place new limits on the emission
amplitude at the rotation frequency of the pulsars.}
@article{ 2019ApJ...879...10A,
title = { Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 20152017 LIGO Data },
journal = { Astrophysical Journal },
year = { 2019 },
month = { July },
volume = { 879 },
number = { 1 },
pages = { 10 },
doi = { 10.3847/15384357/ab20cb },
}
Allsky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO O2 data
{We present results of an allsky search for continuous gravitational
waves (CWs), which can be produced by fast spinning neutron
stars with an asymmetry around their rotation axis, using data
from the second observing run of the Advanced LIGO detectors.
Three different semicoherent methods are used to search in a
gravitationalwave frequency band from 20 to 1922 Hz and a first
frequency derivative from 1 {\texttimes}10$^{8}$ to 2
{\texttimes}10$^{9}$ Hz /s . None of these searches has found
clear evidence for a CW signal, so upper limits on the
gravitationalwave strain amplitude are calculated, which for
this broad range in parameter space are the most sensitive ever
achieved.
}
@article{ 2019PhRvD.100b4004A,
title = { Allsky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO O2 data },
journal = { Physical Review D },
year = { 2019 },
month = { July },
volume = { 100 },
number = { 2 },
pages = { 024004 },
doi = { 10.1103/PhysRevD.100.024004 },
}
Allsky search for short gravitationalwave bursts in the second Advanced LIGO and Advanced Virgo run
{We present the results of a search for shortduration gravitationalwave
transients in the data from the second observing run of Advanced
LIGO and Advanced Virgo. We search for gravitationalwave
transients with a duration of milliseconds to approximately one
second in the 324096 Hz frequency band with minimal assumptions
about the signal properties, thus targeting a wide variety of
sources. We also perform a matchedfilter search for
gravitationalwave transients from cosmic string cusps for which
the waveform is well modeled. The unmodeled search detected
gravitational waves from several binary black hole mergers which
have been identified by previous analyses. No other significant
events have been found by either the unmodeled search or the
cosmic string search. We thus present the search sensitivities
for a variety of signal waveforms and report upper limits on the
source rate density as a function of the characteristic
frequency of the signal. These upper limits are a factor of 3
lower than the first observing run, with a 50\% detection
probability for gravitationalwave emissions with energies of
̃10$^{9}$ M$_{☉}$c$^{2}$ at 153 Hz. For the search dedicated to
cosmic string cusps we consider several loop distribution
models, and present updated constraints from the same search
done in the first observing run.}
@article{ 2019PhRvD.100b4017A,
title = { Allsky search for short gravitationalwave bursts in the second Advanced LIGO and Advanced Virgo run },
journal = { Physical Review D },
year = { 2019 },
month = { July },
volume = { 100 },
number = { 2 },
pages = { 024017 },
doi = { 10.1103/PhysRevD.100.024017 },
}
Tests of General Relativity with GW170817
{The recent discovery by Advanced LIGO and Advanced Virgo of a
gravitational wave signal from a binary neutron star inspiral
has enabled tests of general relativity (GR) with this new type
of source. This source, for the first time, permits tests of
strongfield dynamics of compact binaries in the presence of
matter. In this Letter, we place constraints on the dipole
radiation and possible deviations from GR in the postNewtonian
coefficients that govern the inspiral regime. Bounds on modified
dispersion of gravitational waves are obtained; in combination
with information from the observed electromagnetic counterpart
we can also constrain effects due to large extra dimensions.
Finally, the polarization content of the gravitational wave
signal is studied. The results of all tests performed here show
good agreement with GR.
}
@article{ 2019PhRvL.123a1102A,
title = { Tests of General Relativity with GW170817 },
journal = { Physical Review Letters },
year = { 2019 },
month = { July },
volume = { 123 },
number = { 1 },
pages = { 011102 },
doi = { 10.1103/PhysRevLett.123.011102 },
}
GWTC1: A GravitationalWave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs
{We present the results from three gravitationalwave searches for
coalescing compact binaries with component masses above 1
M$_{☉}$ during the first and second observing runs of the
advanced gravitationalwave detector network. During the first
observing run (O 1 ), from September 12, 2015 to January 19,
2016, gravitational waves from three binary black hole mergers
were detected. The second observing run (O 2 ), which ran from
November 30, 2016 to August 25, 2017, saw the first detection of
gravitational waves from a binary neutron star inspiral, in
addition to the observation of gravitational waves from a total
of seven binary black hole mergers, four of which we report here
for the first time: GW170729, GW170809, GW170818, and GW170823.
For all significant gravitationalwave events, we provide
estimates of the source properties. The detected binary black
holes have total masses between 18.6$_{0.7}$$^{+3.2}$ M$_{☉}$
and 84.4$_{11.1}$$^{+15.8}$ M$_{☉}$ and range in distance
between 320$_{110}$$^{+120}$ and 2840$_{1360}$$^{+1400}$ Mpc .
No neutron starblack hole mergers were detected. In addition to
highly significant gravitationalwave events, we also provide a
list of marginal event candidates with an estimated falsealarm
rate less than 1 per 30 days. From these results over the first
two observing runs, which include approximately one
gravitationalwave detection per 15 days of data searched, we
infer merger rates at the 90\% confidence intervals of 110 3840
Gpc$^{3}$ y$^{1}$ for binary neutron stars and 9.7 101
Gpc$^{3}$ y$^{1}$ for binary black holes assuming fixed
population distributions and determine a neutron starblack hole
merger rate 90\% upper limit of 610 Gpc$^{3}$ y$^{1}$ .
}
@article{ 2019PhRvX...9c1040A,
title = { GWTC1: A GravitationalWave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs },
journal = { Physical Review X },
year = { 2019 },
month = { July },
volume = { 9 },
number = { 3 },
pages = { 031040 },
doi = { 10.1103/PhysRevX.9.031040 },
}
Erratum: {\textquotedblleft}Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 20152017 LIGO Data{\textquotedblright} (2019, ApJ, 879, 10)
@article{ 2019ApJ...882...73A,
title = { Erratum: {\textquotedblleft}Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 20152017 LIGO Data{\textquotedblright} (2019, ApJ, 879, 10) },
journal = { Astrophysical Journal },
year = { 2019 },
month = { September },
volume = { 882 },
number = { 1 },
pages = { 73 },
doi = { 10.3847/15384357/ab3231 },
}
Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo
{We present results on the mass, spin, and redshift distributions with
phenomenological population models using the 10 binary black
hole (BBH) mergers detected in the first and second observing
runs completed by Advanced LIGO and Advanced Virgo. We constrain
properties of the BBH mass spectrum using models with a range of
parameterizations of the BBH mass and spin distributions. We
find that the mass distribution of the more massive BH in such
binaries is well approximated by models with no more than 1\% of
BHs more massive than 45 \{M\}$_{☉ }$ and a powerlaw index of
{\ensuremath{\alpha}} = \{1.3\}$_{1.7}$$^{+1.4}$ (90\%
credibility). We also show that BBHs are unlikely to be composed
of BHs with large spins aligned to the orbital angular momentum.
Modeling the evolution of the BBH merger rate with redshift, we
show that it is flat or increasing with redshift with 93\%
probability. Marginalizing over uncertainties in the BBH
population, we find robust estimates of the BBH merger rate
density of R = \{53.2\}$_{28.2}$$^{+55.8}$ Gpc$^{3}$ yr$^{1}$
(90\% credibility). As the BBH catalog grows in future observing
runs, we expect that uncertainties in the population model
parameters will shrink, potentially providing insights into the
formation of BHs via supernovae, binary interactions of massive
stars, stellar cluster dynamics, and the formation history of
BHs across cosmic time.}
@article{ 2019ApJ...882L..24A,
title = { Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo },
journal = { \apjl },
year = { 2019 },
month = { September },
volume = { 882 },
number = { 2 },
pages = { L24 },
doi = { 10.3847/20418213/ab3800 },
}
Search for the isotropic stochastic background using data from Advanced LIGO's second observing run
{The stochastic gravitationalwave background is a superposition of
sources that are either too weak or too numerous to detect
individually. In this study, we present the results from a
crosscorrelation analysis on data from Advanced LIGO's second
observing run (O2), which we combine with the results of the
first observing run (O1). We do not find evidence for a
stochastic background, so we place upper limits on the
normalized energy density in gravitational waves at the 95\%
credible level of {\ensuremath{\Omega}}$_{GW}$\<6.0
{\texttimes}10$^{8}$ for a frequencyindependent (flat)
background and {\ensuremath{\Omega}}$_{GW}$\<4.8
{\texttimes}10$^{8}$ at 25 Hz for a background of compact
binary coalescences. The upper limit improves over the O1 result
by a factor of 2.8. Additionally, we place upper limits on the
energy density in an isotropic background of scalar and vector
polarized gravitational waves, and we discuss the implication of
these results for models of compact binaries and cosmic string
backgrounds. Finally, we present a conservative estimate of the
correlated broadband noise due to the magnetic Schumann
resonances in O2, based on magnetometer measurements at both the
LIGO Hanford and LIGO Livingston observatories. We find that
correlated noise is well below the O2 sensitivity.}
@article{ 2019PhRvD.100f1101A,
title = { Search for the isotropic stochastic background using data from Advanced LIGO's second observing run },
journal = { Physical Review D },
year = { 2019 },
month = { September },
volume = { 100 },
number = { 6 },
pages = { 061101 },
doi = { 10.1103/PhysRevD.100.061101 },
}
Directional limits on persistent gravitational waves using data from Advanced LIGO's first two observing runs
{We perform an unmodeled search for persistent, directional gravitational
wave (GW) sources using data from the first and second observing
runs of Advanced LIGO. We do not find evidence for any GW
signals. We place limits on the broadband GW flux emitted at 25
Hz from point sources with a power law spectrum at
F$_{{\ensuremath{\alpha}} ,{\ensuremath{\Theta}}}$\<(0.05 
25 ){\texttimes}10$^{8}$ erg cm$^{2}$ s$^{1}$ Hz$^{1}$ and
the (normalized) energy density spectrum in GWs at 25 Hz from
extended sources at {\ensuremath{\Omega}}$_{{\ensuremath{\alpha}
}}$({\ensuremath{\Theta}} )\<(0.19  2.89
){\texttimes}10$^{8}$ sr$^{1}$ where {\ensuremath{\alpha}} is
the spectral index of the energy density spectrum. These
represent improvements of 2.5  3 {\texttimes} over previous
limits. We also consider point sources emitting GWs at a single
frequency, targeting the directions of Sco X1, SN 1987A, and
the Galactic center. The best upper limits on the strain
amplitude of a potential source in these three directions range
from h$_{0}$\<(3.6  4.7 ){\texttimes}10$^{25}$ , 1.5
{\texttimes} better than previous limits set with the same
analysis method. We also report on a marginally significant
outlier at 36.06 Hz. This outlier is not consistent with a
persistent gravitationalwave source as its significance
diminishes when combining all of the available data.
}
@article{ 2019PhRvD.100f2001A,
title = { Directional limits on persistent gravitational waves using data from Advanced LIGO's first two observing runs },
journal = { Physical Review D },
year = { 2019 },
month = { September },
volume = { 100 },
number = { 6 },
pages = { 062001 },
doi = { 10.1103/PhysRevD.100.062001 },
}
Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network
{Gravitationalwave astronomy has been firmly established with the
detection of gravitational waves from the merger of ten stellar
mass binary black holes and a neutron star binary. This paper
reports on the allsky search for gravitational waves from
intermediate mass black hole binaries in the first and second
observing runs of the Advanced LIGO and Virgo network. The
search uses three independent algorithms: two based on matched
filtering of the data with waveform templates of gravitational
wave signals from compact binaries, and a third, model
independent algorithm that employs no signal model for the
incoming signal. No intermediate mass black hole binary event is
detected in this search. Consequently, we place upper limits on
the merger rate density for a family of intermediate mass black
hole binaries. In particular, we choose sources with total
masses M =m$_{1}$+m$_{2}${\ensuremath{\in}}[120 ,800 ] M$_{☉}$
and mass ratios q =m$_{2}$/m$_{1}${\ensuremath{\in}}[0.1 ,1.0 ].
For the first time, this calculation is done using numerical
relativity waveforms (which include higher modes) as models of
the real emitted signal. We place a most stringent upper limit
of 0.20 Gpc$^{3}$ yr$^{1}$ (in comoving units at the 90\%
confidence level) for equalmass binaries with individual masses
m$_{1 ,2}$=100 M$_{☉}$ and dimensionless spins
{\ensuremath{\chi}}$_{1 ,2}$=0.8 aligned with the orbital
angular momentum of the binary. This improves by a factor of ̃5
that reported after Advanced LIGO's first observing run.}
@article{ 2019PhRvD.100f4064A,
title = { Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network },
journal = { Physical Review D },
year = { 2019 },
month = { September },
volume = { 100 },
number = { 6 },
pages = { 064064 },
doi = { 10.1103/PhysRevD.100.064064 },
}
Search for Eccentric Binary Black Hole Mergers with Advanced LIGO and Advanced Virgo during Their First and Second Observing Runs
{When formed through dynamical interactions, stellarmass binary black
holes (BBHs) may retain eccentric orbits (e \> 0.1 at 10 Hz)
detectable by groundbased gravitationalwave detectors.
Eccentricity can therefore be used to differentiate dynamically
formed binaries from isolated BBH mergers. Current template
based gravitationalwave searches do not use waveform models
associated with eccentric orbits, rendering the search less
efficient for eccentric binary systems. Here we present the
results of a search for BBH mergers that inspiral in eccentric
orbits using data from the first and second observing runs (O1
and O2) of Advanced LIGO and Advanced Virgo. We carried out the
search with the coherent WaveBurst algorithm, which uses minimal
assumptions on the signal morphology and does not rely on binary
waveform templates. We show that it is sensitive to binary
mergers with a detection range that is weakly dependent on
eccentricity for all bound systems. Our search did not identify
any new binary merger candidates. We interpret these results in
light of eccentric binary formation models. We rule out
formation channels with rates {\ensuremath{\gtrsim}}100
Gpc$^{3}$ yr$^{1}$ for e \> 0.1, assuming a black hole mass
spectrum with a powerlaw index {\ensuremath{\lesssim}}2.}
@article{ 2019ApJ...883..149A,
title = { Search for Eccentric Binary Black Hole Mergers with Advanced LIGO and Advanced Virgo during Their First and Second Observing Runs },
journal = { Astrophysical Journal },
year = { 2019 },
month = { October },
volume = { 883 },
number = { 2 },
pages = { 149 },
doi = { 10.3847/15384357/ab3c2d },
}
Search for Subsolar Mass Ultracompact Binaries in Advanced LIGO's Second Observing Run
{We present a search for subsolar mass ultracompact objects in data
obtained during Advanced LIGO's second observing run. In
contrast to a previous search of Advanced LIGO data from the
first observing run, this search includes the effects of
component spin on the gravitational waveform. We identify no
viable gravitationalwave candidates consistent with subsolar
mass ultracompact binaries with at least one component between
0.2 M$_{☉}$ 1.0 M$_{☉}$ . We use the null result to constrain
the binary merger rate of (0.2 M$_{☉}$ , 0.2 M$_{☉}$ ) binaries
to be less than 3.7 {\texttimes}{}10$^{5}$ Gpc$^{3}$ yr$^{1}$
and the binary merger rate of (1.0 M$_{☉}$ , 1.0 M$_{☉}$ )
binaries to be less than 5.2 {\texttimes}{}10$^{3}$ Gpc$^{3}$
yr$^{1}$ . Subsolar mass ultracompact objects are not expected
to form via known stellar evolution channels, though it has been
suggested that primordial density fluctuations or particle dark
matter with cooling mechanisms and/or nuclear interactions could
form black holes with subsolar masses. Assuming a particular
primordial black hole (PBH) formation model, we constrain a
population of merging 0.2 M$_{☉}$ black holes to account for
less than 16\% of the dark matter density and a population of
merging 1.0 M$_{☉}$ black holes to account for less than 2\% of
the dark matter density. We discuss how constraints on the
merger rate and dark matter fraction may be extended to
arbitrary black hole population models that predict subsolar
mass binaries.
}
@article{ 2019PhRvL.123p1102A,
title = { Search for Subsolar Mass Ultracompact Binaries in Advanced LIGO's Second Observing Run },
journal = { Physical Review Letters },
year = { 2019 },
month = { October },
volume = { 123 },
number = { 16 },
pages = { 161102 },
doi = { 10.1103/PhysRevLett.123.161102 },
}
First Search for Nontensorial Gravitational Waves from Known Pulsars
{We present results from the first directed search for nontensorial
gravitational waves. While general relativity allows for
tensorial (plus and cross) modes only, a generic metric theory
may, in principle, predict waves with up to six different
polarizations. This analysis is sensitive to continuous signals
of scalar, vector, or tensor polarizations, and does not rely on
any specific theory of gravity. After searching data from the
first observation run of the advanced LIGO detectors for signals
at twice the rotational frequency of 200 known pulsars, we find
no evidence of gravitational waves of any polarization. We
report the first upper limits for scalar and vector strains,
finding values comparable in magnitude to previously published
limits for tensor strain. Our results may be translated into
constraints on specific alternative theories of gravity.
}
@article{ 2018PhRvL.120c1104A,
title = { First Search for Nontensorial Gravitational Waves from Known Pulsars },
journal = { Physical Review Letters },
year = { 2018 },
month = { January },
volume = { 120 },
number = { 3 },
pages = { 031104 },
doi = { 10.1103/PhysRevLett.120.031104 },
}
Allsky search for longduration gravitational wave transients in the first Advanced LIGO observing run
{We present the results of a search for longduration gravitational wave
transients in the data of the LIGO Hanford and LIGO Livingston
second generation detectors between
\textbackslashnewcommand\{\textbackslashOOneStart\}\{12
\raisebox{0.5ex}\textasciitildeSeptember
\raisebox{0.5ex}\textasciitilde2015\} \textbackslashnewcommand\
{\textbackslashOOneStartShort\}\{September
\raisebox{0.5ex}\textasciitilde2015\}
\textbackslashOOneStartShort and \textbackslashnewcommand\{\text
backslashOOneStop\}\{19\raisebox{0.5ex}\textasciitilde January
\raisebox{0.5ex}\textasciitilde2016\} \textbackslashnewcommand\
{\textbackslashOOneStopShort\}\{January\raisebox{0.5ex}\textasc
iitilde 2016\} \textbackslashOOneStopShort , with a total
observational time of \textbackslashnewcommand\{\textbackslashOO
neLivetime\}\{49\raisebox{0.5ex}\textasciitilded\}
\textbackslashOOneLivetime . The search targets gravitational
wave transients of 10500{\,}s duration in a frequency band of
242048 Hz, with minimal assumptions about the signal waveform,
polarization, source direction, or time of occurrence. No
significant events were observed. As a result we set 90\%
confidence upper limits on the rate of longduration
gravitational wave transients for different types of
gravitational wave signals. We also show that the search is
sensitive to sources in the Galaxy emitting at
least{\,}{\,}̃10$^{8}$
\textbackslashnewcommand\{\textbackslashmsuncd\}\{M$_{☉ c\^2}$\}
\textbackslashnewcommand\{\textbackslashmsun\}\{M$_{☉}$\}
\{\textbackslashmsuncd\} in gravitational waves.
}
@article{ 2018CQGra..35f5009A,
title = { Allsky search for longduration gravitational wave transients in the first Advanced LIGO observing run },
journal = { Classical and Quantum Gravity },
year = { 2018 },
month = { March },
volume = { 35 },
number = { 6 },
pages = { 065009 },
doi = { 10.1088/13616382/aaab76 },
}
GW170817: Implications for the Stochastic GravitationalWave Background from Compact Binary Coalescences
{The LIGO Scientific and Virgo Collaborations have announced the event
GW170817, the first detection of gravitational waves from the
coalescence of two neutron stars. The merger rate of binary
neutron stars estimated from this event suggests that distant,
unresolvable binary neutron stars create a significant
astrophysical stochastic gravitationalwave background. The
binary neutron star component will add to the contribution from
binary black holes, increasing the amplitude of the total
astrophysical background relative to previous expectations. In
the Advanced LIGOVirgo frequency band most sensitive to
stochastic backgrounds (near 25 Hz), we predict a total
astrophysical background with amplitude
{\ensuremath{\Omega}}$_{GW}$(f =25 Hz )=1.
8$_{1.3}$$^{+2.7}${\texttimes}10$^{9}$ with 90\% confidence,
compared with {\ensuremath{\Omega}}$_{GW}$(f =25 Hz )=1.
1$_{0.7}$$^{+1.2}${\texttimes}10$^{9}$ from binary black holes
alone. Assuming the most probable rate for compact binary
mergers, we find that the total background may be detectable
with a signaltonoiseratio of 3 after 40 months of total
observation time, based on the expected timeline for Advanced
LIGO and Virgo to reach their design sensitivity.
}
@article{ 2018PhRvL.120i1101A,
title = { GW170817: Implications for the Stochastic GravitationalWave Background from Compact Binary Coalescences },
journal = { Physical Review Letters },
year = { 2018 },
month = { March },
volume = { 120 },
number = { 9 },
pages = { 091101 },
doi = { 10.1103/PhysRevLett.120.091101 },
}
Prospects for observing and localizing gravitationalwave transients with Advanced LIGO, Advanced Virgo and KAGRA
Living Reviews in Relativity, 21, 3
Gravitational waves Gravitationalwave detectors Electromagnetic counterparts Data analysis General Relativity and Quantum Cosmology Astrophysics  High Energy Astrophysical Phenomena
 arxiv:1304.0670
 doi:10.1007/s4111401800129

Show bibtex
Show abstract
{We present possible observing scenarios for the Advanced LIGO, Advanced
Virgo and KAGRA gravitationalwave detectors over the next
decade, with the intention of providing information to the
astronomy community to facilitate planning for multimessenger
astronomy with gravitational waves. We estimate the sensitivity
of the network to transient gravitationalwave signals, and
study the capability of the network to determine the sky
location of the source. We report our findings for
gravitationalwave transients, with particular focus on
gravitationalwave signals from the inspiral of binary neutron
star systems, which are the most promising targets for multi
messenger astronomy. The ability to localize the sources of the
detected signals depends on the geographical distribution of the
detectors and their relative sensitivity, and 90\% credible
regions can be as large as thousands of square degrees when only
two sensitive detectors are operational. Determining the sky
position of a significant fraction of detected signals to areas
of 520 deg\^2 requires at least three detectors of sensitivity
within a factor of ̃ 2 of each other and with a broad frequency
bandwidth. When all detectors, including KAGRA and the third
LIGO detector in India, reach design sensitivity, a significant
fraction of gravitationalwave signals will be localized to a
few square degrees by gravitationalwave observations alone.}
@article{ 2018LRR....21....3A,
title = { Prospects for observing and localizing gravitationalwave transients with Advanced LIGO, Advanced Virgo and KAGRA },
journal = { Living Reviews in Relativity },
year = { 2018 },
month = { April },
volume = { 21 },
number = { 1 },
pages = { 3 },
doi = { 10.1007/s4111401800129 },
}
Constraints on cosmic strings using data from the first Advanced LIGO observing run
{Cosmic strings are topological defects which can be formed in grand
unified theory scale phase transitions in the early universe.
They are also predicted to form in the context of string theory.
The main mechanism for a network of NambuGoto cosmic strings to
lose energy is through the production of loops and the
subsequent emission of gravitational waves, thus offering an
experimental signature for the existence of cosmic strings. Here
we report on the analysis conducted to specifically search for
gravitationalwave bursts from cosmic string loops in the data
of Advanced LIGO 20152016 observing run (O1). No evidence of
such signals was found in the data, and as a result we set upper
limits on the cosmic string parameters for three recent loop
distribution models. In this paper, we initially derive
constraints on the string tension G {\ensuremath{\mu}} and the
intercommutation probability, using not only the burst analysis
performed on the O1 data set but also results from the
previously published LIGO stochastic O1 analysis, pulsar timing
arrays, cosmic microwave background and bigbang nucleosynthesis
experiments. We show that these data sets are complementary in
that they probe gravitational waves produced by cosmic string
loops during very different epochs. Finally, we show that the
data sets exclude large parts of the parameter space of the
three loop distribution models we consider.
}
@article{ 2018PhRvD..97j2002A,
title = { Constraints on cosmic strings using data from the first Advanced LIGO observing run },
journal = { Physical Review D },
year = { 2018 },
month = { May },
volume = { 97 },
number = { 10 },
pages = { 102002 },
doi = { 10.1103/PhysRevD.97.102002 },
}
Full band allsky search for periodic gravitational waves in the O1 LIGO data
{We report on a new allsky search for periodic gravitational waves in
the frequency band 4752000 Hz and with a frequency time
derivative in the range of [1.0 ,+0.1 ] {\texttimes}1 0$^{8}$
Hz /s . Potential signals could be produced by a nearby spinning
and slightly nonaxisymmetric isolated neutron star in our
Galaxy. This search uses the data from Advanced LIGO's first
observational run O1. No gravitationalwave signals were
observed, and upper limits were placed on their strengths. For
completeness, results from the separately published low
frequency search 20475 Hz are included as well. Our lowest
upper limit on worstcase (linearly polarized) strain amplitude
h$_{0}$ is ̃4 {\texttimes}1 0$^{25}$ near 170 Hz, while at the
high end of our frequency range, we achieve a worstcase upper
limit of 1.3 {\texttimes}1 0$^{24}$. For a circularly polarized
source (most favorable orientation), the smallest upper limit
obtained is ̃1.5 {\texttimes}1 0$^{25}$.
}
@article{ 2018PhRvD..97j2003A,
title = { Full band allsky search for periodic gravitational waves in the O1 LIGO data },
journal = { Physical Review D },
year = { 2018 },
month = { May },
volume = { 97 },
number = { 10 },
pages = { 102003 },
doi = { 10.1103/PhysRevD.97.102003 },
}
Search for Tensor, Vector, and Scalar Polarizations in the Stochastic GravitationalWave Background
{The detection of gravitational waves with Advanced LIGO and Advanced
Virgo has enabled novel tests of general relativity, including
direct study of the polarization of gravitational waves. While
general relativity allows for only two tensor gravitationalwave
polarizations, general metric theories can additionally predict
two vector and two scalar polarizations. The polarization of
gravitational waves is encoded in the spectral shape of the
stochastic gravitationalwave background, formed by the
superposition of cosmological and individually unresolved
astrophysical sources. Using data recorded by Advanced LIGO
during its first observing run, we search for a stochastic
background of generically polarized gravitational waves. We find
no evidence for a background of any polarization, and place the
first direct bounds on the contributions of vector and scalar
polarizations to the stochastic background. Under loguniform
priors for the energy in each polarization, we limit the energy
densities of tensor, vector, and scalar modes at 95\%
credibility to {\ensuremath{\Omega}}$_{0}$$^{T}$\<5.58
{\texttimes}10$^{8}$ ,
{\ensuremath{\Omega}}$_{0}$$^{V}$\<6.35 {\texttimes}10$^{8}$
, and {\ensuremath{\Omega}}$_{0}$$^{S}$\<1.08
{\texttimes}10$^{7}$ at a reference frequency f$_{0}$=25 Hz .
}
@article{ 2018PhRvL.120t1102A,
title = { Search for Tensor, Vector, and Scalar Polarizations in the Stochastic GravitationalWave Background },
journal = { Physical Review Letters },
year = { 2018 },
month = { May },
volume = { 120 },
number = { 20 },
pages = { 201102 },
doi = { 10.1103/PhysRevLett.120.201102 },
}
GW170817: Measurements of Neutron Star Radii and Equation of State
{On 17 August 2017, the LIGO and Virgo observatories made the first
direct detection of gravitational waves from the coalescence of
a neutron star binary system. The detection of this
gravitationalwave signal, GW170817, offers a novel opportunity
to directly probe the properties of matter at the extreme
conditions found in the interior of these stars. The initial,
minimalassumption analysis of the LIGO and Virgo data placed
constraints on the tidal effects of the coalescing bodies, which
were then translated to constraints on neutron star radii. Here,
we expand upon previous analyses by working under the hypothesis
that both bodies were neutron stars that are described by the
same equation of state and have spins within the range observed
in Galactic binary neutron stars. Our analysis employs two
methods: the use of equationofstateinsensitive relations
between various macroscopic properties of the neutron stars and
the use of an efficient parametrization of the defining function
p ({\ensuremath{\rho}} ) of the equation of state itself. From
the LIGO and Virgo data alone and the first method, we measure
the two neutron star radii as R$_{1}$=10.8$_{1.7}$$^{+2.0}$ km
for the heavier star and R$_{2}$=10.7$_{1.5}$$^{+2.1}$ km for
the lighter star at the 90\% credible level. If we additionally
require that the equation of state supports neutron stars with
masses larger than 1.97 M$_{☉}$ as required from electromagnetic
observations and employ the equationofstate parametrization,
we further constrain R$_{1}$=11.9$_{1.4}$$^{+1.4}$ km and
R$_{2}$=11.9$_{1.4}$$^{+1.4}$ km at the 90\% credible level.
Finally, we obtain constraints on p ({\ensuremath{\rho}} ) at
supranuclear densities, with pressure at twice nuclear
saturation density measured at
3.5$_{1.7}$$^{+2.7}${\texttimes}{}10$^{34}$ dyn cm$^{2}$ at
the 90\% level.
}
@article{ 2018PhRvL.121p1101A,
title = { GW170817: Measurements of Neutron Star Radii and Equation of State },
journal = { Physical Review Letters },
year = { 2018 },
month = { October },
volume = { 121 },
number = { 16 },
pages = { 161101 },
doi = { 10.1103/PhysRevLett.121.161101 },
}
transientlunatic/minke: Luce Bay
@article{ 2018zndo...1699336W,
author = {Williams} and Daniel and {anonymouscommitter},
title = { transientlunatic/minke: Luce Bay },
year = { 2018 },
month = { November },
doi = { 10.5281/zenodo.1699336 },
}
Search for SubsolarMass Ultracompact Binaries in Advanced LIGO's First Observing Run
{We present the first Advanced LIGO and Advanced Virgo search for
ultracompact binary systems with component masses between 0.2
M$_{☉}$ 1.0 M$_{☉}$ using data taken between September 12, 2015
and January 19, 2016. We find no viable gravitational wave
candidates. Our null result constrains the coalescence rate of
monochromatic (delta function) distributions of nonspinning (0.2
M$_{☉}$ , 0.2 M$_{☉}$ ) ultracompact binaries to be less than
1.0 {\texttimes}{}10$^{6}$ Gpc$^{3}$ yr$^{1}$ and the
coalescence rate of a similar distribution of (1.0 M$_{☉}$ , 1.0
M$_{☉}$ ) ultracompact binaries to be less than 1.9
{\texttimes}{}10$^{4}$ Gpc$^{3}$ yr$^{1}$ (at 90\%
confidence). Neither black holes nor neutron stars are expected
to form below ̃1 M$_{☉}$ through conventional stellar evolution,
though it has been proposed that similarly low mass black holes
could be formed primordially through density fluctuations in the
early Universe and contribute to the dark matter density. The
interpretation of our constraints in the primordial black hole
dark matter paradigm is highly model dependent; however, under a
particular primordial black hole binary formation scenario we
constrain monochromatic primordial black hole populations of 0.2
M$_{☉}$ to be less than 33\% of the total dark matter density
and monochromatic populations of 1.0 M$_{☉}$ to be less than 5\%
of the dark matter density. The latter strengthens the presently
placed bounds from microlensing surveys of massive compact halo
objects (MACHOs) provided by the MACHO and EROS Collaborations.
}
@article{ 2018PhRvL.121w1103A,
title = { Search for SubsolarMass Ultracompact Binaries in Advanced LIGO's First Observing Run },
journal = { Physical Review Letters },
year = { 2018 },
month = { December },
volume = { 121 },
number = { 23 },
pages = { 231103 },
doi = { 10.1103/PhysRevLett.121.231103 },
}
Constraints On Short, Hard GammaRay Burst Beaming Angles From Gravitational Wave Observations
The first detection of a binary neutron star merger, GW170817, and an associated short gammaray burst confirmed that neutron star mergers are responsible for at least some of these bursts. The prompt gamma ray emission from these events is thought to be highly relativistically beamed. We present a method for inferring limits on the extent of this beaming by comparing the number of short gammaray bursts observed electromagnetically to the number of neutron star binary mergers detected in gravitational waves. We demonstrate that an observing run comparable to the expected Advanced LIGO 20162017 run would be capable of placing limits on the beaming angle of approximately θ∈(2.88∘,14.15∘), given one binary neutron star detection. We anticipate that after a year of observations with Advanced LIGO at design sensitivity in 2020 these constraints would improve to θ∈(8.10∘,14.95∘).
@article{ 2017arXiv171202585W,
author = { Daniel Williams } and { James Clark } and { Andrew Williamson } and { Ik Siong Heng },
title = { Constraints On Short, Hard GammaRay Burst Beaming Angles From Gravitational Wave Observations },
journal = { Astrophysical Journal },
year = { 2018 },
volume = { 858 },
doi = { 10.3847/15384357/aab847 },
}
Allsky search for short gravitationalwave bursts in the first Advanced LIGO run
{We present the results from an allsky search for shortduration
gravitational waves in the data of the first run of the Advanced
LIGO detectors between September 2015 and January 2016. The
search algorithms use minimal assumptions on the signal
morphology, so they are sensitive to a wide range of sources
emitting gravitational waves. The analyses target transient
signals with duration ranging from milliseconds to seconds over
the frequency band of 32 to 4096 Hz. The first observed
gravitationalwave event, GW150914, has been detected with high
confidence in this search; the other known gravitationalwave
event, GW151226, falls below the search's sensitivity. Besides
GW150914, all of the search results are consistent with the
expected rate of accidental noise coincidences. Finally, we
estimate ratedensity limits for a broad range of nonbinary
blackhole transient gravitationalwave sources as a function of
their gravitational radiation emission energy and their
characteristic frequency. These ratedensity upper limits are
stricter than those previously published by an order of
magnitude.
}
@article{ 2017PhRvD..95d2003A,
title = { Allsky search for short gravitationalwave bursts in the first Advanced LIGO run },
journal = { Physical Review D },
year = { 2017 },
month = { February },
volume = { 95 },
number = { 4 },
pages = { 042003 },
doi = { 10.1103/PhysRevD.95.042003 },
}
Upper Limits on the Stochastic GravitationalWave Background from Advanced LIGO's First Observing Run
{A wide variety of astrophysical and cosmological sources are expected to
contribute to a stochastic gravitationalwave background.
Following the observations of GW150914 and GW151226, the rate
and mass of coalescing binary black holes appear to be greater
than many previous expectations. As a result, the stochastic
background from unresolved compact binary coalescences is
expected to be particularly loud. We perform a search for the
isotropic stochastic gravitationalwave background using data
from Advanced Laser Interferometer Gravitational Wave
Observatory's (aLIGO) first observing run. The data display no
evidence of a stochastic gravitationalwave signal. We constrain
the dimensionless energy density of gravitational waves to be
{\ensuremath{\Omega}}$_{0}$\<1.7 {\texttimes}10$^{7}$ with
95\% confidence, assuming a flat energy density spectrum in the
most sensitive part of the LIGO band (2086 Hz). This is a
factor of ̃33 times more sensitive than previous measurements.
We also constrain arbitrary powerlaw spectra. Finally, we
investigate the implications of this search for the background
of binary black holes using an astrophysical model for the
background.
}
@article{ 2017PhRvL.118l1101A,
title = { Upper Limits on the Stochastic GravitationalWave Background from Advanced LIGO's First Observing Run },
journal = { Physical Review Letters },
year = { 2017 },
month = { March },
volume = { 118 },
number = { 12 },
pages = { 121101 },
doi = { 10.1103/PhysRevLett.118.121101 },
}
Directional Limits on Persistent Gravitational Waves from Advanced LIGO's First Observing Run
Physical Review Letters, 118, 121102
General Relativity and Quantum Cosmology Astrophysics  Cosmology and Nongalactic Astrophysics Astrophysics  High Energy Astrophysical Phenomena Astrophysics  Instrumentation and Methods for Astrophysics
 arxiv:1612.02030
 doi:10.1103/PhysRevLett.118.121102

Show bibtex
Show abstract
{We employ gravitationalwave radiometry to map the stochastic
gravitational wave background expected from a variety of
contributing mechanisms and test the assumption of isotropy
using data from the Advanced Laser Interferometer Gravitational
Wave Observatory's (aLIGO) first observing run. We also search
for persistent gravitational waves from point sources with only
minimal assumptions over the 201726 Hz frequency band. Finding
no evidence of gravitational waves from either point sources or
a stochastic background, we set limits at 90\% confidence. For
broadband point sources, we report upper limits on the
gravitational wave energy flux per unit frequency in the range
F$_{{\ensuremath{\alpha}} ,{\ensuremath{\Theta}}}$(f )\<(0.1
 56 ){\texttimes}10$^{8}$ erg cm$^{2}$ s$^{1}$ Hz$^{1}$(f
/25 Hz )$^{{\ensuremath{\alpha}} 1}$ depending on the sky
location {\ensuremath{\Theta}} and the spectral power index
{\ensuremath{\alpha}} . For extended sources, we report upper
limits on the fractional gravitational wave energy density
required to close the Universe of {\ensuremath{\Omega}} (f
,{\ensuremath{\Theta}} )\<(0.39  7.6 ){\texttimes}10$^{8}$
sr$^{1}$(f /25 Hz )$^{{\ensuremath{\alpha}}}$ depending on
{\ensuremath{\Theta}} and {\ensuremath{\alpha}} . Directed
searches for narrowband gravitational waves from astrophysically
interesting objects (Scorpius X1, Supernova 1987 A, and the
Galactic Center) yield median frequencydependent limits on
strain amplitude of h$_{0}$\<(6.7 ,5.5 , and 7.0
){\texttimes}10$^{25}$ , respectively, at the most sensitive
detector frequencies between 130175 Hz. This represents a mean
improvement of a factor of 2 across the band compared to
previous searches of this kind for these sky locations,
considering the different quantities of strain constrained in
each case.
}
@article{ 2017PhRvL.118l1102A,
title = { Directional Limits on Persistent Gravitational Waves from Advanced LIGO's First Observing Run },
journal = { Physical Review Letters },
year = { 2017 },
month = { March },
volume = { 118 },
number = { 12 },
pages = { 121102 },
doi = { 10.1103/PhysRevLett.118.121102 },
}
First Search for Gravitational Waves from Known Pulsars with Advanced LIGO
{We present the result of searches for gravitational waves from 200
pulsars using data from the first observing run of the Advanced
LIGO detectors. We find no significant evidence for a
gravitationalwave signal from any of these pulsars, but we are
able to set the most constraining upper limits yet on their
gravitationalwave amplitudes and ellipticities. For eight of
these pulsars, our upper limits give bounds that are
improvements over the indirect spindown limit values. For
another 32, we are within a factor of 10 of the spindown limit,
and it is likely that some of these will be reachable in future
runs of the advanced detector. Taken as a whole, these new
results improve on previous limits by more than a factor of two.}
@article{ 2017ApJ...839...12A,
title = { First Search for Gravitational Waves from Known Pulsars with Advanced LIGO },
journal = { Astrophysical Journal },
year = { 2017 },
month = { April },
volume = { 839 },
number = { 1 },
pages = { 12 },
doi = { 10.3847/15384357/aa677f },
}
Effects of waveform model systematics on the interpretation of GW150914
{Parameter estimates of GW150914 were obtained using Bayesian inference,
based on three semianalytic waveform models for binary black
hole coalescences. These waveform models differ from each other
in their treatment of black hole spins, and all three models
make some simplifying assumptions, notably to neglect sub
dominant waveform harmonic modes and orbital eccentricity.
Furthermore, while the models are calibrated to agree with
waveforms obtained by full numerical solutions of
Einstein{\textquoteright}s equations, any such calibration is
accurate only to some nonzero tolerance and is limited by the
accuracy of the underlying phenomenology, availability, quality,
and parameterspace coverage of numerical simulations. This
paper complements the original analyses of GW150914 with an
investigation of the effects of possible systematic errors in
the waveform models on estimates of its source parameters. To
test for systematic errors we repeat the original Bayesian
analysis on mock signals from numerical simulations of a series
of binary configurations with parameters similar to those found
for GW150914. Overall, we find no evidence for a systematic bias
relative to the statistical error of the original parameter
recovery of GW150914 due to modeling approximations or modeling
inaccuracies. However, parameter biases are found to occur for
some configurations disfavored by the data of GW150914: for
binaries inclined edgeon to the detector over a small range of
choices of polarization angles, and also for eccentricities
greater than{\,}{\,}̃0.05. For signals with higher signalto
noise ratio than GW150914, or in other regions of the binary
parameter space (lower masses, larger mass ratios, or higher
spins), we expect that systematic errors in current waveform
models may impact gravitationalwave measurements, making more
accurate models desirable for future observations.
}
@article{ 2017CQGra..34j4002A,
title = { Effects of waveform model systematics on the interpretation of GW150914 },
journal = { Classical and Quantum Gravity },
year = { 2017 },
month = { May },
volume = { 34 },
number = { 10 },
pages = { 104002 },
doi = { 10.1088/13616382/aa6854 },
}
Search for Gravitational Waves Associated with GammaRay Bursts during the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B
{We present the results of the search for gravitational waves (GWs)
associated with {\ensuremath{\gamma}}ray bursts detected during
the first observing run of the Advanced Laser Interferometer
GravitationalWave Observatory (LIGO). We find no evidence of a
GW signal for any of the 41 {\ensuremath{\gamma}}ray bursts for
which LIGO data are available with sufficient duration. For all
{\ensuremath{\gamma}}ray bursts, we place lower bounds on the
distance to the source using the optimistic assumption that GWs
with an energy of \{10\}$^{2}$\{M\}$_{☉ }$\{c\}$^{2}$ were
emitted within the 16500 Hz band, and we find a median 90\%
confidence limit of 71 Mpc at 150 Hz. For the subset of 19
short/hard {\ensuremath{\gamma}}ray bursts, we place lower
bounds on distance with a median 90\% confidence limit of 90 Mpc
for binary neutron star (BNS) coalescences, and 150 and 139 Mpc
for neutron starblack hole coalescences with spins aligned to
the orbital angular momentum and in a generic configuration,
respectively. These are the highest distance limits ever
achieved by GW searches. We also discuss in detail the results
of the search for GWs associated with GRB 150906B, an event that
was localized by the InterPlanetary Network near the local
galaxy NGC 3313, which is at a luminosity distance of 54 Mpc (z
= 0.0124). Assuming the {\ensuremath{\gamma}}ray emission is
beamed with a jet halfopening angle {\ensuremath{\leq}}slant
30\^\textbackslashcirc , we exclude a BNS and a neutron star
black hole in NGC 3313 as the progenitor of this event with
confidence \>99\%. Further, we exclude such progenitors up to
a distance of 102 Mpc and 170 Mpc, respectively.}
@article{ 2017ApJ...841...89A,
title = { Search for Gravitational Waves Associated with GammaRay Bursts during the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B },
journal = { Astrophysical Journal },
year = { 2017 },
month = { June },
volume = { 841 },
number = { 2 },
pages = { 89 },
doi = { 10.3847/15384357/aa6c47 },
}
Search for gravitational waves from Scorpius X1 in the first Advanced LIGO observing run with a hidden Markov model
{Results are presented from a semicoherent search for continuous
gravitational waves from the brightest lowmass Xray binary,
Scorpius X1, using data collected during the first Advanced
LIGO observing run. The search combines a frequency domain
matched filter (Besselweighted F statistic) with a hidden
Markov model to track wandering of the neutron star spin
frequency. No evidence of gravitational waves is found in the
frequency range 60650 Hz. Frequentist 95\% confidence strain
upper limits, h$_{0}$$^{95 \%}$=4.0 {\texttimes}1 0$^{25}$, 8.3
{\texttimes}1 0$^{25}$, and 3.0 {\texttimes}1 0$^{25}$ for
electromagnetically restricted source orientation, unknown
polarization, and circular polarization, respectively, are
reported at 106 Hz. They are {\ensuremath{\leq}}10 times higher
than the theoretical torquebalance limit at 106 Hz.
}
@article{ 2017PhRvD..95l2003A,
title = { Search for gravitational waves from Scorpius X1 in the first Advanced LIGO observing run with a hidden Markov model },
journal = { Physical Review D },
year = { 2017 },
month = { June },
volume = { 95 },
number = { 12 },
pages = { 122003 },
doi = { 10.1103/PhysRevD.95.122003 },
}
GW170104: Observation of a 50SolarMass Binary Black Hole Coalescence at Redshift 0.2
{We describe the observation of GW170104, a gravitationalwave signal
produced by the coalescence of a pair of stellarmass black
holes. The signal was measured on January 4, 2017 at
10{\ensuremath{:}}11:58.6 UTC by the twin advanced detectors of
the Laser Interferometer GravitationalWave Observatory during
their second observing run, with a network signaltonoise ratio
of 13 and a false alarm rate less than 1 in 70 000 years. The
inferred component black hole masses are 31.
2$_{6.0}$$^{+8.4}$M$_{☉}$ and 19. 4$_{5.9}$$^{+5.3}$ M$_{☉}$
(at the 90\% credible level). The black hole spins are best
constrained through measurement of the effective inspiral spin
parameter, a massweighted combination of the spin components
perpendicular to the orbital plane,
{\ensuremath{\chi}}$_{eff}$=0.1 2$_{0.30}$$^{+0.21}$ . This
result implies that spin configurations with both component
spins positively aligned with the orbital angular momentum are
disfavored. The source luminosity distance is 88
0$_{390}$$^{+450}$ Mpc corresponding to a redshift of z =0.1
8$_{0.07}$$^{+0.08}$ . We constrain the magnitude of
modifications to the gravitationalwave dispersion relation and
perform null tests of general relativity. Assuming that
gravitons are dispersed in vacuum like massive particles, we
bound the graviton mass to m$_{g}${\ensuremath{\leq}}7.7
{\texttimes}10$^{23}$ eV /c$^{2}$ . In all cases, we find that
GW170104 is consistent with general relativity.}
@article{ 2017PhRvL.118v1101A,
title = { GW170104: Observation of a 50SolarMass Binary Black Hole Coalescence at Redshift 0.2 },
journal = { Physical Review Letters },
year = { 2017 },
month = { June },
volume = { 118 },
number = { 22 },
pages = { 221101 },
doi = { 10.1103/PhysRevLett.118.221101 },
}
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
{During their first observational run, the two Advanced LIGO detectors
attained an unprecedented sensitivity, resulting in the first
direct detections of gravitationalwave signals produced by
stellarmass binary black hole systems. This paper reports on an
allsky search for gravitational waves (GWs) from merging
intermediate mass black hole binaries (IMBHBs). The combined
results from two independent search techniques were used in this
study: the first employs a matchedfilter algorithm that uses a
bank of filters covering the GW signal parameter space, while
the second is a generic search for GW transients (bursts). No
GWs from IMBHBs were detected; therefore, we constrain the rate
of several classes of IMBHB mergers. The most stringent limit is
obtained for black holes of individual mass 100 M$_{☉}$ , with
spins aligned with the binary orbital angular momentum. For such
systems, the merger rate is constrained to be less than 0.93
Gpc$^{3}$ yr$^{1}$ in comoving units at the 90\% confidence
level, an improvement of nearly 2 orders of magnitude over
previous upper limits.
}
@article{ 2017PhRvD..96b2001A,
title = { Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO },
journal = { Physical Review D },
year = { 2017 },
month = { July },
volume = { 96 },
number = { 2 },
pages = { 022001 },
doi = { 10.1103/PhysRevD.96.022001 },
}
Search for highenergy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube
{The Advanced LIGO observatories detected gravitational waves from two
binary black hole mergers during their first observation run
(O1). We present a highenergy neutrino followup search for the
second gravitational wave event, GW151226, as well as for
gravitational wave candidate LVT151012. We find two and four
neutrino candidates detected by IceCube, and one and zero
detected by Antares, within {\ensuremath{\pm}}500 s around the
respective gravitational wave signals, consistent with the
expected background rate. None of these neutrino candidates are
found to be directionally coincident with GW151226 or LVT151012.
We use nondetection to constrain isotropicequivalent high
energy neutrino emission from GW151226, adopting the GW event's
3D localization, to less than 2 {\texttimes}1 {}0$^{51}$ 2
{\texttimes}1 {}0$^{54}$ erg .
}
@article{ 2017PhRvD..96b2005A,
title = { Search for highenergy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube },
journal = { Physical Review D },
year = { 2017 },
month = { July },
volume = { 96 },
number = { 2 },
pages = { 022005 },
doi = { 10.1103/PhysRevD.96.022005 },
}
Upper Limits on Gravitational Waves from Scorpius X1 from a Modelbased Crosscorrelation Search in Advanced LIGO Data
{We present the results of a semicoherent search for continuous
gravitational waves from the lowmass Xray binary Scorpius X1,
using data from the first Advanced LIGO observing run. The
search method uses details of the modeled, parametrized
continuous signal to combine coherently data separated by less
than a specified coherence time, which can be adjusted to trade
off sensitivity against computational cost. A search was
conducted over the frequency range 252000 \{Hz\}, spanning the
current observationally constrained range of binary orbital
parameters. No significant detection candidates were found, and
frequencydependent upper limits were set using a combination of
sensitivity estimates and simulated signal injections. The most
stringent upper limit was set at 175 \{Hz\}, with comparable
limits set across the most sensitive frequency range from 100 to
200 \{Hz\}. At this frequency, the 95\% upper limit on the
signal amplitude h $_{0}$ is 2.3{\texttimes} \{10\}$^{25}$
marginalized over the unknown inclination angle of the neutron
star{\textquoteright}s spin, and 8.0{\texttimes} \{10\}$^{26}$
assuming the best orientation (which results in circularly
polarized gravitational waves). These limits are a factor of 34
stronger than those set by other analyses of the same data, and
a factor of ̃7 stronger than the best upper limits set using
data from Initial LIGO science runs. In the vicinity of 100
\{Hz\}, the limits are a factor of between 1.2 and 3.5 above the
predictions of the torque balance model, depending on the
inclination angle; if the most likely inclination angle of
44{\textdegree} is assumed, they are within a factor of 1.7.}
@article{ 2017ApJ...847...47A,
title = { Upper Limits on Gravitational Waves from Scorpius X1 from a Modelbased Crosscorrelation Search in Advanced LIGO Data },
journal = { Astrophysical Journal },
year = { 2017 },
month = { September },
volume = { 847 },
number = { 1 },
pages = { 47 },
doi = { 10.3847/15384357/aa86f0 },
}
Allsky search for periodic gravitational waves in the O1 LIGO data
{We report on an allsky search for periodic gravitational waves in the
frequency band 20475 Hz and with a frequency time derivative in
the range of [1.0 ,+0.1 ] {\texttimes}10$^{8}$ Hz /s . Such a
signal could be produced by a nearby spinning and slightly
nonaxisymmetric isolated neutron star in our galaxy. This search
uses the data from Advanced LIGO's first observational run, O1.
No periodic gravitational wave signals were observed, and upper
limits were placed on their strengths. The lowest upper limits
on worstcase (linearly polarized) strain amplitude h$_{0}$ are
̃4 {\texttimes}10$^{25}$ near 170 Hz. For a circularly
polarized source (most favorable orientation), the smallest
upper limits obtained are ̃1.5 {\texttimes}10$^{25}$. These
upper limits refer to all sky locations and the entire range of
frequency derivative values. For a populationaveraged ensemble
of sky locations and stellar orientations, the lowest upper
limits obtained for the strain amplitude are ̃2.5
{\texttimes}10$^{25}$.
}
@article{ 2017PhRvD..96f2002A,
title = { Allsky search for periodic gravitational waves in the O1 LIGO data },
journal = { Physical Review D },
year = { 2017 },
month = { September },
volume = { 96 },
number = { 6 },
pages = { 062002 },
doi = { 10.1103/PhysRevD.96.062002 },
}
Multimessenger Observations of a Binary Neutron Star Merger
{On 2017 August 17 a binary neutron star coalescence candidate (later
designated GW170817) with merger time 12:41:04 UTC was observed
through gravitational waves by the Advanced LIGO and Advanced
Virgo detectors. The Fermi Gammaray Burst Monitor independently
detected a gammaray burst (GRB 170817A) with a time delay of ̃
1.7 \{\{s\}\} with respect to the merger time. From the
gravitationalwave signal, the source was initially localized to
a sky region of 31 deg$^{2}$ at a luminosity distance of
\{40\}$_{8}$$^{+8}$ Mpc and with component masses consistent
with neutron stars. The component masses were later measured to
be in the range 0.86 to 2.26 \{M\}$_{☉ }$. An extensive
observing campaign was launched across the electromagnetic
spectrum leading to the discovery of a bright optical transient
(SSS17a, now with the IAU identification of AT 2017gfo) in NGC
4993 (at ̃ 40 \{\{Mpc\}\}) less than 11 hours after the merger
by the OneMeter, Two Hemisphere (1M2H) team using the 1 m Swope
Telescope. The optical transient was independently detected by
multiple teams within an hour. Subsequent observations targeted
the object and its environment. Early ultraviolet observations
revealed a blue transient that faded within 48 hours. Optical
and infrared observations showed a redward evolution over ̃10
days. Following early nondetections, Xray and radio emission
were discovered at the transient's position ̃ 9 and ̃ 16 days,
respectively, after the merger. Both the Xray and radio
emission likely arise from a physical process that is distinct
from the one that generates the UV/optical/nearinfrared
emission. No ultrahighenergy gammarays and no neutrino
candidates consistent with the source were found in followup
searches. These observations support the hypothesis that
GW170817 was produced by the merger of two neutron stars in NGC
4993 followed by a short gammaray burst (GRB 170817A) and a
kilonova/macronova powered by the radioactive decay of rprocess
nuclei synthesized in the ejecta.
Any correspondence should
be addressed to .}
@article{ 2017ApJ...848L..12A,
title = { Multimessenger Observations of a Binary Neutron Star Merger },
journal = { \apjl },
year = { 2017 },
month = { October },
volume = { 848 },
number = { 2 },
pages = { L12 },
doi = { 10.3847/20418213/aa91c9 },
}
Gravitational Waves and GammaRays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
{On 2017 August 17, the gravitationalwave event GW170817 was observed by
the Advanced LIGO and Virgo detectors, and the gammaray burst
(GRB) GRB 170817A was observed independently by the Fermi Gamma
ray Burst Monitor, and the AntiCoincidence Shield for the
Spectrometer for the International GammaRay Astrophysics
Laboratory. The probability of the nearsimultaneous temporal
and spatial observation of GRB 170817A and GW170817 occurring by
chance is 5.0{\texttimes} \{10\}$^{8}$. We therefore confirm
binary neutron star mergers as a progenitor of short GRBs. The
association of GW170817 and GRB 170817A provides new insight
into fundamental physics and the origin of short GRBs. We use
the observed time delay of (+1.74+/ 0.05) \{\{s\}\} between GRB
170817A and GW170817 to: (I) constrain the difference between
the speed of gravity and the speed of light to be between
3{\texttimes} \{10\}$^{15}$ and +7{\texttimes} \{10\}$^{16}$
times the speed of light, (II) place new bounds on the violation
of Lorentz invariance, (III) present a new test of the
equivalence principle by constraining the Shapiro delay between
gravitational and electromagnetic radiation. We also use the
time delay to constrain the size and bulk Lorentz factor of the
region emitting the gammarays. GRB 170817A is the closest short
GRB with a known distance, but is between 2 and 6 orders of
magnitude less energetic than other bursts with measured
redshift. A new generation of gammaray detectors, and
subthreshold searches in existing detectors, will be essential
to detect similar short bursts at greater distances. Finally, we
predict a joint detection rate for the Fermi Gammaray Burst
Monitor and the Advanced LIGO and Virgo detectors of 0.11.4 per
year during the 20182019 observing run and 0.31.7 per year at
design sensitivity.}
@article{ 2017ApJ...848L..13A,
title = { Gravitational Waves and GammaRays from a Binary Neutron Star Merger: GW170817 and GRB 170817A },
journal = { \apjl },
year = { 2017 },
month = { October },
volume = { 848 },
number = { 2 },
pages = { L13 },
doi = { 10.3847/20418213/aa920c },
}
GW170814: A ThreeDetector Observation of Gravitational Waves from a Binary Black Hole Coalescence
{On August 14, 2017 at 10{\ensuremath{:}}30:43 UTC, the Advanced Virgo
detector and the two Advanced LIGO detectors coherently observed
a transient gravitationalwave signal produced by the
coalescence of two stellar mass black holes, with a falsealarm
rate of {\ensuremath{\lesssim}}1 in 27 000 years. The signal was
observed with a threedetector network matchedfilter signalto
noise ratio of 18. The inferred masses of the initial black
holes are 30. 5$_{3.0}$$^{+5.7}$M$_{☉}$ and 25
.3$_{4.2}$$^{+2.8}$M$_{☉}$ (at the 90\% credible level). The
luminosity distance of the source is 54 0$_{210}$$^{+130}$ Mpc
, corresponding to a redshift of z =0.1 1$_{0.04}$$^{+0.03}$. A
network of three detectors improves the sky localization of the
source, reducing the area of the 90\% credible region from 1160
deg$^{2}$ using only the two LIGO detectors to 60 deg$^{2}$
using all three detectors. For the first time, we can test the
nature of gravitationalwave polarizations from the antenna
response of the LIGOVirgo network, thus enabling a new class of
phenomenological tests of gravity.
}
@article{ 2017PhRvL.119n1101A,
title = { GW170814: A ThreeDetector Observation of Gravitational Waves from a Binary Black Hole Coalescence },
journal = { Physical Review Letters },
year = { 2017 },
month = { October },
volume = { 119 },
number = { 14 },
pages = { 141101 },
doi = { 10.1103/PhysRevLett.119.141101 },
}
GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
{On August 17, 2017 at 12{\ensuremath{:}}41:04 UTC the Advanced LIGO and
Advanced Virgo gravitationalwave detectors made their first
observation of a binary neutron star inspiral. The signal,
GW170817, was detected with a combined signaltonoise ratio of
32.4 and a falsealarmrate estimate of less than one per 8.0
{\texttimes}{}10$^{4}$ years . We infer the component masses of
the binary to be between 0.86 and 2.26 M$_{☉}$ , in agreement
with masses of known neutron stars. Restricting the component
spins to the range inferred in binary neutron stars, we find the
component masses to be in the range 1.17  1.60 M$_{☉}$ , with
the total mass of the system 2.7 4$_{0.01}$$^{+0.04}$M$_{☉}$ .
The source was localized within a sky region of 28 deg$^{2}$
(90\% probability) and had a luminosity distance of 4
0$_{14}$$^{+8}$ Mpc , the closest and most precisely localized
gravitationalwave signal yet. The association with the
{\ensuremath{\gamma}} ray burst GRB 170817A, detected by Fermi
GBM 1.7 s after the coalescence, corroborates the hypothesis of
a neutron star merger and provides the first direct evidence of
a link between these mergers and short {\ensuremath{\gamma}}
ray bursts. Subsequent identification of transient counterparts
across the electromagnetic spectrum in the same location further
supports the interpretation of this event as a neutron star
merger. This unprecedented joint gravitational and
electromagnetic observation provides insight into astrophysics,
dense matter, gravitation, and cosmology.
}
@article{ 2017PhRvL.119p1101A,
title = { GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral },
journal = { Physical Review Letters },
year = { 2017 },
month = { October },
volume = { 119 },
number = { 16 },
pages = { 161101 },
doi = { 10.1103/PhysRevLett.119.161101 },
}
A gravitationalwave standard siren measurement of the Hubble constant
{On 17 August 2017, the Advanced LIGO and Virgo detectors observed the
gravitationalwave event GW170817{\textemdash}a strong signal
from the merger of a binary neutronstar system. Less than two
seconds after the merger, a {\ensuremath{\gamma}}ray burst (GRB
170817A) was detected within a region of the sky consistent with
the LIGOVirgoderived location of the gravitationalwave
source. This sky region was subsequently observed by optical
astronomy facilities, resulting in the identification 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 {\textquoteleft}multimessenger{\textquoteright}
astronomical observation. Such observations enable GW170817 to
be used as a {\textquoteleft}standard siren{\textquoteright}
(meaning that the absolute distance to the source can be
determined directly from the gravitationalwave 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 {\textquoteleft}distance ladder{\textquoteright}:
the gravitationalwave 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
measurements, 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.}
@article{ 2017Natur.551...85A,
title = { A gravitationalwave standard siren measurement of the Hubble constant },
journal = { \nat },
year = { 2017 },
month = { November },
volume = { 551 },
number = { 7678 },
pages = { 8588 },
doi = { 10.1038/nature24471 },
}
VizieR Online Data Catalog: Gravitational waves search from known PSR with LIGO (Abbott+, 2017)
{We have obtained timings for 200 known pulsars. Timing was performed
using the 42ft telescope and Lovell telescope at Jodrell Bank
(UK), the 26m telescope at Hartebeesthoek (South Africa), the
Parkes radio telescope (Australia), the Nancay Decimetric Radio
Telescope (France), the Arecibo Observatory (Puerto Rico) and
the Fermi Large Area Telescope (LAT). Of these, 122 have been
targeted in previous campaigns (Aasi+ 2014, J/ApJ/785/119),
while 78 are new to this search.
(1 data file).}
@article{ 2017yCat..18390012A,
title = { VizieR Online Data Catalog: Gravitational waves search from known PSR with LIGO (Abbott+, 2017) },
journal = { VizieR Online Data Catalog },
year = { 2017 },
month = { November },
pages = { J/ApJ/839/12 },
}
Search for Highenergy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory
{The Advanced LIGO and Advanced Virgo observatories recently discovered
gravitational waves from a binary neutron star inspiral. A short
gammaray burst (GRB) that followed the merger of this binary
was also recorded by the Fermi Gammaray Burst Monitor (Fermi
GBM), and the AntiCoincidence Shield for the Spectrometer for
the International GammaRay Astrophysics Laboratory (INTEGRAL),
indicating particle acceleration by the source. The precise
location of the event was determined by optical detections of
emission following the merger. We searched for highenergy
neutrinos from the merger in the GeVEeV energy range using the
ANTARES, IceCube, and Pierre Auger Observatories. No neutrinos
directionally coincident with the source were detected within
{\ensuremath{\pm}}500 s around the merger time. Additionally, no
MeV neutrino burst signal was detected coincident with the
merger. We further carried out an extended search in the
direction of the source for highenergy neutrinos within the 14
day period following the merger, but found no evidence of
emission. We used these results to probe dissipation mechanisms
in relativistic outflows driven by the binary neutron star
merger. The nondetection is consistent with model predictions
of short GRBs observed at a large offaxis angle.}
@article{ 2017ApJ...850L..35A,
title = { Search for Highenergy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory },
journal = { \apjl },
year = { 2017 },
month = { December },
volume = { 850 },
number = { 2 },
pages = { L35 },
doi = { 10.3847/20418213/aa9aed },
}
Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
{The source of the gravitationalwave (GW) signal GW170817, very likely a
binary neutron star merger, was also observed
electromagnetically, providing the first multimessenger
observations of this type. The twoweeklong electromagnetic
(EM) counterpart had a signature indicative of an rprocess
induced optical transient known as a kilonova. This Letter
examines how the mass of the dynamical ejecta can be estimated
without a direct electromagnetic observation of the kilonova,
using GW measurements and a phenomenological model calibrated to
numerical simulations of mergers with dynamical ejecta.
Specifically, we apply the model to the binary masses inferred
from the GW measurements, and use the resulting mass of the
dynamical ejecta to estimate its contribution (without the
effects of wind ejecta) to the corresponding kilonova light
curves from various models. The distributions of dynamical
ejecta mass range between
\{M\}$_{\{ej}$\}=\{10\}$^{3}$\{10\}$^{2}$ \{M\}$_{☉ }$ for
various equations of state, assuming that the neutron stars are
rotating slowly. In addition, we use our estimates of the
dynamical ejecta mass and the neutron star merger rates inferred
from GW170817 to constrain the contribution of events like this
to the rprocess element abundance in the Galaxy when ejecta
mass from postmerger winds is neglected. We find that if
{\ensuremath{\gtrsim}}10\% of the matter dynamically ejected
from binary neutron star (BNS) mergers is converted to rprocess
elements, GW170817like BNS mergers could fully account for the
amount of rprocess material observed in the Milky Way.}
@article{ 2017ApJ...850L..39A,
title = { Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817 },
journal = { \apjl },
year = { 2017 },
month = { December },
volume = { 850 },
number = { 2 },
pages = { L39 },
doi = { 10.3847/20418213/aa9478 },
}
On the Progenitor of Binary Neutron Star Merger GW170817
{On 2017 August 17 the merger of two compact objects with masses
consistent with two neutron stars was discovered through
gravitationalwave (GW170817), gammaray (GRB 170817A), and
optical (SSS17a/AT 2017gfo) observations. The optical source was
associated with the earlytype galaxy NGC 4993 at a distance of
just ̃40 Mpc, consistent with the gravitationalwave
measurement, and the merger was localized to be at a projected
distance of ̃2 kpc away from the galaxy{\textquoteright}s
center. We use this minimal set of facts and the mass posteriors
of the two neutron stars to derive the first constraints on the
progenitor of GW170817 at the time of the second supernova (SN).
We generate simulated progenitor populations and follow the
threedimensional kinematic evolution from binary neutron star
(BNS) birth to the merger time, accounting for preSN galactic
motion, for considerably different input distributions of the
progenitor mass, preSN semimajor axis, and SNkick velocity.
Though not considerably tight, we find these constraints to be
comparable to those for Galactic BNS progenitors. The derived
constraints are very strongly influenced by the requirement of
keeping the binary bound after the second SN and having the
merger occur relatively close to the center of the galaxy. These
constraints are insensitive to the galaxy{\textquoteright}s star
formation history, provided the stellar populations are older
than 1 Gyr.}
@article{ 2017ApJ...850L..40A,
title = { On the Progenitor of Binary Neutron Star Merger GW170817 },
journal = { \apjl },
year = { 2017 },
month = { December },
volume = { 850 },
number = { 2 },
pages = { L40 },
doi = { 10.3847/20418213/aa93fc },
}
Erratum: {\textquotedblleft}First Search for Gravitational Waves from Known Pulsars with Advanced LIGO{\textquotedblright} (2017, ApJ, 839, 12)
@article{ 2017ApJ...851...71A,
title = { Erratum: {\textquotedblleft}First Search for Gravitational Waves from Known Pulsars with Advanced LIGO{\textquotedblright} (2017, ApJ, 839, 12) },
journal = { Astrophysical Journal },
year = { 2017 },
month = { December },
volume = { 851 },
number = { 1 },
pages = { 71 },
doi = { 10.3847/15384357/aa9aee },
}
Search for Postmerger Gravitational Waves from the Remnant of the Binary Neutron Star Merger GW170817
{The first observation of a binary neutron star (NS) coalescence by the
Advanced LIGO and Advanced Virgo gravitationalwave (GW)
detectors offers an unprecedented opportunity to study matter
under the most extreme conditions. After such a merger, a
compact remnant is left over whose nature depends primarily on
the masses of the inspiraling objects and on the equation of
state of nuclear matter. This could be either a black hole (BH)
or an NS, with the latter being either longlived or too massive
for stability implying delayed collapse to a BH. Here, we
present a search for GWs from the remnant of the binary NS
merger GW170817 using data from Advanced LIGO and Advanced
Virgo. We search for short ({\ensuremath{\lesssim}}1 s) and
intermediateduration ({\ensuremath{\lesssim}}500 s) signals,
which include GW emission from a hypermassive NS or supramassive
NS, respectively. We find no signal from the postmerger
remnant. Our derived strain upper limits are more than an order
of magnitude larger than those predicted by most models. For
short signals, our best upper limit on the root sum square of
the GW strain emitted from 14 kHz is \{h\}$_{\{rss}$\}$^{50 \%
}$=2.1{\texttimes} \{10\}$^{22}$ \{\{Hz\}\}$^{1/2}$ at 50\%
detection efficiency. For intermediateduration signals, our
best upper limit at 50\% detection efficiency is
\{h\}$_{\{rss}$\}$^{50 \% }$=8.4{\texttimes} \{10\}$^{22}$
\{\{Hz\}\}$^{1/2}$ for a millisecond magnetar model, and
\{h\}$_{\{rss}$\}$^{50 \% }$=5.9{\texttimes} \{10\}$^{22}$
\{\{Hz\}\}$^{1/2}$ for a barmode model. These results indicate
that postmerger emission from a similar event may be detectable
when advanced detectors reach design sensitivity or with next
generation detectors.}
@article{ 2017ApJ...851L..16A,
title = { Search for Postmerger Gravitational Waves from the Remnant of the Binary Neutron Star Merger GW170817 },
journal = { \apjl },
year = { 2017 },
month = { December },
volume = { 851 },
number = { 1 },
pages = { L16 },
doi = { 10.3847/20418213/aa9a35 },
}
GW170608: Observation of a 19 Solarmass Binary Black Hole Coalescence
{On 2017 June 8 at 02:01:16.49 UTC, a gravitationalwave (GW) signal from
the merger of two stellarmass black holes was observed by the
two Advanced Laser Interferometer GravitationalWave Observatory
detectors with a network signaltonoise ratio of 13. This
system is the lightest black hole binary so far observed, with
component masses of \{12\}$_{2}$$^{+7}$ \{M\}$_{☉ }$ and
\{7\}$_{2}$$^{+2}$ \{M\}$_{☉ }$ (90\% credible intervals).
These lie in the range of measured black hole masses in lowmass
Xray binaries, thus allowing us to compare black holes detected
through GWs with electromagnetic observations. The
source{\textquoteright}s luminosity distance is
\{340\}$_{140}$$^{+140}$ \{Mpc\}, corresponding to redshift
\{0.07\}$_{0.03}$$^{+0.03}$. We verify that the signal waveform
is consistent with the predictions of general relativity.}
@article{ 2017ApJ...851L..35A,
title = { GW170608: Observation of a 19 Solarmass Binary Black Hole Coalescence },
journal = { \apjl },
year = { 2017 },
month = { December },
volume = { 851 },
number = { 2 },
pages = { L35 },
doi = { 10.3847/20418213/aa9f0c },
}
First lowfrequency Einstein@Home allsky search for continuous gravitational waves in Advanced LIGO data
{We report results of a deep allsky search for periodic gravitational
waves from isolated neutron stars in data from the first
Advanced LIGO observing run. This search investigates the low
frequency range of Advanced LIGO data, between 20 and 100 Hz,
much of which was not explored in initial LIGO. The search was
made possible by the computing power provided by the volunteers
of the Einstein@Home project. We find no significant signal
candidate and set the most stringent upper limits to date on the
amplitude of gravitational wave signals from the target
population, corresponding to a sensitivity depth of 48.7 [1
/{\ensuremath{\sqrt{}}}\{Hz \}] . At the frequency of best
strain sensitivity, near 100 Hz, we set 90\% confidence upper
limits of 1.8 {\texttimes}1 0$^{25}$. At the low end of our
frequency range, 20 Hz, we achieve upper limits of 3.9
{\texttimes}1 0$^{24}$. At 55 Hz we can exclude sources with
ellipticities greater than 1 0$^{5}$ within 100 pc of Earth
with fiducial value of the principal moment of inertia of
{}10$^{38}$ kg m$^{2}$ .
}
@article{ 2017PhRvD..96l2004A,
title = { First lowfrequency Einstein@Home allsky search for continuous gravitational waves in Advanced LIGO data },
journal = { Physical Review D },
year = { 2017 },
month = { December },
volume = { 96 },
number = { 12 },
pages = { 122004 },
doi = { 10.1103/PhysRevD.96.122004 },
}
First narrowband search for continuous gravitational waves from known pulsars in advanced detector data
{Spinning neutron stars asymmetric with respect to their rotation axis
are potential sources of continuous gravitational waves for
groundbased interferometric detectors. In the case of known
pulsars a fully coherent search, based on matched filtering,
which uses the position and rotational parameters obtained from
electromagnetic observations, can be carried out. Matched
filtering maximizes the signaltonoise (SNR) ratio, but a large
sensitivity loss is expected in case of even a very small
mismatch between the assumed and the true signal parameters. For
this reason, narrowband analysis methods have been developed,
allowing a fully coherent search for gravitational waves from
known pulsars over a fraction of a hertz and several spindown
values. In this paper we describe a narrowband search of 11
pulsars using data from Advanced LIGO's first observing run.
Although we have found several initial outliers, further studies
show no significant evidence for the presence of a gravitational
wave signal. Finally, we have placed upper limits on the signal
strain amplitude lower than the spindown limit for 5 of the 11
targets over the bands searched; in the case of J18131749 the
spindown limit has been beaten for the first time. For an
additional 3 targets, the median upper limit across the search
bands is below the spindown limit. This is the most sensitive
narrowband search for continuous gravitational waves carried
out so far.
}
@article{ 2017PhRvD..96l2006A,
title = { First narrowband search for continuous gravitational waves from known pulsars in advanced detector data },
journal = { Physical Review D },
year = { 2017 },
month = { December },
volume = { 96 },
number = { 12 },
pages = { 122006 },
doi = { 10.1103/PhysRevD.96.122006 },
}
Observing gravitationalwave transient GW150914 with minimal assumptions
{The gravitationalwave signal GW150914 was first identified on September
14, 2015, by searches for shortduration gravitationalwave
transients. These searches identify timecorrelated transients
in multiple detectors with minimal assumptions about the signal
morphology, allowing them to be sensitive to gravitational waves
emitted by a wide range of sources including binary black hole
mergers. Over the observational period from September 12 to
October 20, 2015, these transient searches were sensitive to
binary black hole mergers similar to GW150914 to an average
distance of ̃600 Mpc . In this paper, we describe the analyses
that first detected GW150914 as well as the parameter estimation
and waveform reconstruction techniques that initially identified
GW150914 as the merger of two black holes. We find that the
reconstructed waveform is consistent with the signal from a
binary black hole merger with a chirp mass of ̃30 M$_{☉}$ and a
total mass before merger of ̃70 M$_{☉}$ in the detector frame.
}
@article{ 2016PhRvD..93l2004A,
title = { Observing gravitationalwave transient GW150914 with minimal assumptions },
journal = { Physical Review D },
year = { 2016 },
month = { June },
volume = { 93 },
number = { 12 },
pages = { 122004 },
doi = { 10.1103/PhysRevD.93.122004 },
}
Tests of General Relativity with GW150914
{The LIGO detection of GW150914 provides an unprecedented opportunity to
study the twobody motion of a compactobject binary in the
largevelocity, highly nonlinear regime, and to witness the
final merger of the binary and the excitation of uniquely
relativistic modes of the gravitational field. We carry out
several investigations to determine whether GW150914 is
consistent with a binary blackhole merger in general
relativity. We find that the final remnant's mass and spin, as
determined from the lowfrequency (inspiral) and highfrequency
(postinspiral) phases of the signal, are mutually consistent
with the binary blackhole solution in general relativity.
Furthermore, the data following the peak of GW150914 are
consistent with the leastdamped quasinormal mode inferred from
the mass and spin of the remnant black hole. By using waveform
models that allow for parametrized generalrelativity violations
during the inspiral and merger phases, we perform quantitative
tests on the gravitationalwave phase in the dynamical regime
and we determine the first empirical bounds on several high
order postNewtonian coefficients. We constrain the graviton
Compton wavelength, assuming that gravitons are dispersed in
vacuum in the same way as particles with mass, obtaining a
90\%confidence lower bound of {}10$^{13}$ km . In conclusion,
within our statistical uncertainties, we find no evidence for
violations of general relativity in the genuinely strongfield
regime of gravity.
}
@article{ 2016PhRvL.116v1101A,
title = { Tests of General Relativity with GW150914 },
journal = { Physical Review Letters },
year = { 2016 },
month = { June },
volume = { 116 },
number = { 22 },
pages = { 221101 },
doi = { 10.1103/PhysRevLett.116.221101 },
}
VizieR Online Data Catalog: Bayesian method for detecting stellar flares (Pitkin+, 2014)
M. Pitkin,
D. Williams,
L. Fletcher,
S.~D.~T. Grant
VizieR Online Data Catalog, J/MNRAS/445/2268
Stars: flare Effective temperatures

Show bibtex
Show abstract
{We present a Bayesianoddsratiobased algorithm for detecting stellar
flares in lightcurve data. We assume flares are described by a
model in which there is a rapid rise with a halfGaussian
profile, followed by an exponential decay. Our signal model also
contains a polynomial background model required to fit
underlying lightcurve variations in the data, which could
otherwise partially mimic a flare. We characterize the false
alarm probability and efficiency of this method under the
assumption that any unmodelled noise in the data is Gaussian,
and compare it with a simpler thresholding method based on that
used in Walkowicz et al. We find our method has a significant
increase in detection efficiency for low signaltonoise ratio
(S/N) flares. For a conservative false alarm probability our
method can detect 95 per cent of flares with S/N less than 20,
as compared to S/N of 25 for the simpler method. We also test
how well the assumption of Gaussian noise holds by applying the
method to a selection of 'quiet' Kepler stars. As an example we
have applied our method to a selection of stars in Kepler
Quarter 1 data. The method finds 687 flaring stars with a total
of 1873 flares after vetos have been applied. For these flares
we have made preliminary characterizations of their durations
and and S/N.
(1 data file).
}
@article{ 2015yCat..74452268P,
author = { Pitkin, M } and { Williams, D } and { Fletcher, L } and { Grant, S },
title = { VizieR Online Data Catalog: Bayesian method for detecting stellar flares (Pitkin+, 2014) },
journal = { VizieR Online Data Catalog },
year = { 2015 },
month = { May },
pages = { J/MNRAS/445/2268 },
}
BayesFlare: Bayesian method for detecting stellar flares
M. Pitkin,
D. Williams,
L. Fletcher,
S.~D.~T. Grant
, ascl:1407.015
Software
 arxiv:1407.015

Show bibtex
@article{ 2014ascl.soft07015P,
author = { Pitkin, M } and { Williams, D } and { Fletcher, L } and { Grant, S },
title = { BayesFlare: Bayesian method for detecting stellar flares },
year = { 2014 },
month = { July },
pages = { ascl:1407.015 },
}
A Bayesian method for detecting stellar flares
{We present a Bayesianoddsratiobased algorithm for detecting stellar
flares in lightcurve data. We assume flares are described by a
model in which there is a rapid rise with a halfGaussian
profile, followed by an exponential decay. Our signal model also
contains a polynomial background model required to fit
underlying lightcurve variations in the data, which could
otherwise partially mimic a flare. We characterize the false
alarm probability and efficiency of this method under the
assumption that any unmodelled noise in the data is Gaussian,
and compare it with a simpler thresholding method based on that
used in Walkowicz et al. We find our method has a significant
increase in detection efficiency for low signaltonoise ratio
(S/N) flares. For a conservative false alarm probability our
method can detect 95 per cent of flares with S/N less than 20,
as compared to S/N of 25 for the simpler method. We also test
how well the assumption of Gaussian noise holds by applying the
method to a selection of `quiet' Kepler stars. As an example we
have applied our method to a selection of stars in Kepler
Quarter 1 data. The method finds 687 flaring stars with a total
of 1873 flares after vetos have been applied. For these flares
we have made preliminary characterizations of their durations
and and S/N.}
@article{ 2014MNRAS.445.2268P,
author = { Pitkin, M } and { Williams, D } and { Fletcher, L } and { Grant, S },
title = { A Bayesian method for detecting stellar flares },
journal = { \mnras },
year = { 2014 },
month = { December },
volume = { 445 },
number = { 3 },
pages = { 22682284 },
doi = { 10.1093/mnras/stu1889 },
}
A Bayesian method for detecting stellar flares
We present a Bayesianoddsratiobased algorithm for detecting stellar flares in light curve data. We assume flares are described by a model in which there is a rapid rise with a halfGaussian profile, followed by an exponential decay. Our signal model also contains a polynomial background model. This is required to fit underlying light curve variations that are expected in the data, which could otherwise partially mimic a flare. We characterise the false alarm probability and efficiency of this method and compare it with a simpler thresholding method based on that used in Walkowicz et al (2011). We find our method has a significant increase in detection efficiency for low signaltonoise ratio (S/N) flares. For a conservative false alarm probability our method can detect 95% of flares with S/N less than ~20, as compared to S/N of ~25 for the simpler method. As an example we have applied our method to a selection of stars in Kepler Quarter 1 data. The method finds 687 flaring stars with a total of 1873 flares after vetos have been applied. For these flares we have characterised their durations and and signaltonoise ratios.
@article{ 2014MNRAS.445.2268P,
author = Matthew Pitkin and Daniel Williams and Lyndsay Fletcher and Samuel Grant,
title = { A Bayesian method for detecting stellar flares },
journal = { Monthly Notices of the Royal Astronomical Society },
year = { 2014 },
volume = { 445 },
pages = { 22682284 },
doi = { 10.1093/mnras/stu1889 },
}