publications | Li-Wei Wei

2024

Temperature effects in narrow-linewidth optical cavity control with a surrogate quasi-second-harmonic field

Li-Wei Wei, Jan Hendrik Põld, Dennis Schmelzer, and 2 more authors

Appl. Opt., May 2024

Abs

Fabry–Perot cavities are widely used in precision interferometric applications. Various techniques have been developed to achieve the resonance condition via the direct interrogation of the cavity with the main laser field of interest. Some use cases, however, require a surrogate field for cavity control. In this study, we construct a bichromatic cavity to study the surrogate control approach, where the main and the surrogate fields are related by the second-harmonic generation with nonlinear optics. We experimentally verify the temperature dependence of the differential reflection phase of a dielectric coating design optimized for the surrogate control approach of the optical cavities of the light-shining-through-a-wall experiment Any Light Particle Search II and develop a comprehensive cavity model for quasi-second-harmonic resonances that considers also other important factors, such as the Gouy phase shift, for a detailed analysis of the surrogate control approach.
Optimized dielectric mirror coating designs for quasi-harmonic cavity resonance

Li-Wei Wei, Harold Hollis, Benno Willke, and 2 more authors

Appl. Opt., May 2024

Abs

High-finesse optical cavities have a wide range of applications, some of which are bichromatic. The successful operation of high-finesse bichromatic cavities can demand careful control on the temperature dependence of the wavelength-dependent reflection phase from the dielectric mirror coatings that constitute the optical cavity. We present dielectric coating designs that are optimized for minimal differential change in the reflection phase between a quasi-second-harmonic field and its fundamental field under temperature changes. These designs guarantee cavity resonance at a wavelength of interest via the control of its quasi-harmonic field. The proposed coating designs are additionally examined for their sensitivity to manufacturing errors in the coating layer thickness with promising results.
Towards the first axion search results of the Any Light Particle Search II experiment

Li-Wei Wei

PoS, May 2024

2022

Design of the ALPS II optical system

M. Diaz Ortiz, J. Gleason, H. Grote, and 16 more authors

Physics of the Dark Universe, May 2022

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The Any Light Particle Search II (ALPSII) is an experiment currently being built at DESY in Hamburg, Germany, that will use a light-shining-through-a-wall (LSW) approach to search for axion-like particles. ALPSII represents a significant step forward for these types of experiments as it will use 24 superconducting dipole magnets, along with dual, high-finesse, 122m long optical cavities. This paper gives the first comprehensive recipe for the realization of the idea, proposed over 30 years ago, to use optical cavities before and after the wall to increase the power of the regenerated photon signal. The experiment is designed to achieve a sensitivity to the coupling between axion-like particles and photons down to gαγγ=2×10−11GeV−1 for masses below 0.1meV, more than three orders of magnitude beyond the sensitivity of previous laboratory experiments. The layout and main components that define ALPSII are discussed along with plans for reaching design sensitivity. An accompanying paper (Hallal et al., (2021)) offers a more in-depth description of the heterodyne detection scheme, the first of two independent detection systems that will be implemented in ALPSII.

2021

All-sky search in early O3 LIGO data for continuous gravitational-wave signals from unknown neutron stars in binary systems

R. Abbott, T. D. Abbott, S. Abraham, and 1367 more authors

Phys. Rev. D, Mar 2021
Tests of general relativity with binary black holes from the second LIGO-Virgo gravitational-wave transient catalog

R. Abbott, T. D. Abbott, S. Abraham, and 1344 more authors

Phys. Rev. D, Jun 2021
Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo’s third observing run

R. Abbott, T. D. Abbott, S. Abraham, and 1584 more authors

Phys. Rev. D, Jul 2021
Search for anisotropic gravitational-wave backgrounds using data from Advanced LIGO and Advanced Virgo’s first three observing runs

R. Abbott, T. D. Abbott, S. Abraham, and 1587 more authors

Phys. Rev. D, Jul 2021
All-sky search for continuous gravitational waves from isolated neutron stars in the early O3 LIGO data

R. Abbott, T. D. Abbott, S. Abraham, and 1585 more authors

Phys. Rev. D, Oct 2021
Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run

R. Abbott, T. D. Abbott, S. Abraham, and 1580 more authors

Phys. Rev. Lett., Jun 2021
GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo during the First Half of the Third Observing Run

R. Abbott, T. D. Abbott, S. Abraham, and 1349 more authors

Phys. Rev. X, Jun 2021
A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 1188 more authors

The Astrophysical Journal, Mar 2021

Abs

This paper presents the gravitational-wave measurement of the Hubble constant (H 0) using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart of the binary neutron star GW170817 led to the first standard-siren measurement of H 0. Here we additionally use binary black hole detections in conjunction with galaxy catalogs and report a joint measurement. Our updated measurement is H 0 = km s−1 Mpc−1 (68.3% of the highest density posterior interval with a flat-in-log prior) which is an improvement by a factor of 1.04 (about 4%) over the GW170817-only value of km s−1 Mpc−1. A significant additional contribution currently comes from GW170814, a loud and well-localized detection from a part of the sky thoroughly covered by the Dark Energy Survey. With numerous detections anticipated over the upcoming years, an exhaustive understanding of other systematic effects are also going to become increasingly important. These results establish the path to cosmology using gravitational-wave observations with and without transient electromagnetic counterparts.
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO–Virgo Run O3a

R. Abbott, T. D. Abbott, S. Abraham, and 1250 more authors

The Astrophysical Journal, Jul 2021

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We search for gravitational-wave transients associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the first part of the third observing run of Advanced LIGO and Advanced Virgo (2019 April 1 15:00 UTC–2019 October 1 15:00 UTC). A total of 105 GRBs were analyzed using a search for generic gravitational-wave transients; 32 GRBs were analyzed with a search that specifically targets neutron star binary mergers as short GRB progenitors. We find no significant evidence for gravitational-wave signals associated with the GRBs that we followed up, nor for a population of unidentified subthreshold signals. We consider several source types and signal morphologies, and report for these lower bounds on the distance to each GRB.
Diving below the Spin-down Limit: Constraints on Gravitational Waves from the Energetic Young Pulsar PSR J0537-6910

R. Abbott, T. D. Abbott, S. Abraham, and 1589 more authors

The Astrophysical Journal Letters, May 2021

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We present a search for quasi-monochromatic gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537−6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using Neutron star Interior Composition Explorer (NICER) data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537−6910 has the largest spin-down luminosity of any pulsar and exhibits fRequent and strong glitches. Analyses of its long-term and interglitch braking indices provide intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a time-varying mass quadrupole moment. Its 62 Hz rotation frequency also puts its possible gravitational-wave emission in the most sensitive band of the LIGO/Virgo detectors. Motivated by these considerations, we search for gravitational-wave emission at both once and twice the rotation frequency from PSR J0537−6910. We find no signal, however, and report upper limits. Assuming a rigidly rotating triaxial star, our constraints reach below the gravitational-wave spin-down limit for this star for the first time by more than a factor of 2 and limit gravitational waves from the l = m = 2 mode to account for less than 14% of the spin-down energy budget. The fiducial equatorial ellipticity is constrained to less than about 3 ×10−5, which is the third best constraint for any young pulsar.
Population Properties of Compact Objects from the Second LIGO–Virgo Gravitational-Wave Transient Catalog

R. Abbott, T. D. Abbott, S. Abraham, and 1338 more authors

The Astrophysical Journal Letters, May 2021

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We report on the population of 47 compact binary mergers detected with a false-alarm rate of < in the second LIGO–Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at or a power law with a Gaussian feature peaking at (90% credible interval). While the primary mass distribution must extend to or beyond, only of systems have primary masses greater than . Second, we find that a fraction of BBH systems have component spins misaligned with the orbital angular momentum, giving rise to precession of the orbital plane. Moreover, %–% of BBH systems have spins tilted by more than 90°, giving rise to a negative effective inspiral spin parameter, . Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing are dynamically assembled. Third, we estimate merger rates, finding for BBHs and for binary neutron stars. We find that the BBH rate likely increases with redshift ( credibility) but not faster than the star formation rate ( credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.
Constraints from LIGO O3 Data on Gravitational-wave Emission Due to R-modes in the Glitching Pulsar PSR J0537–6910

R. Abbott, T. D. Abbott, S. Abraham, and 1592 more authors

The Astrophysical Journal, Nov 2021

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We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537–6910 using data from the LIGO–Virgo Collaboration observing run O3. PSR J0537–6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochs between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86–97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode-driven spin-down in PSR J0537–6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation.
Search for Lensing Signatures in the Gravitational-Wave Observations from the First Half of LIGO–Virgo’s Third Observing Run

R. Abbott, T. D. Abbott, S. Abraham, and 1377 more authors

The Astrophysical Journal, Dec 2021

Abs

We search for signatures of gravitational lensing in the gravitational-wave signals from compact binary coalescences detected by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo during O3a, the first half of their third observing run. We study: (1) the expected rate of lensing at current detector sensitivity and the implications of a non-observation of strong lensing or a stochastic gravitational-wave background on the merger-rate density at high redshift; (2) how the interpretation of individual high-mass events would change if they were found to be lensed; (3) the possibility of multiple images due to strong lensing by galaxies or galaxy clusters; and (4) possible wave-optics effects due to point-mass microlenses. Several pairs of signals in the multiple-image analysis show similar parameters and, in this sense, are nominally consistent with the strong lensing hypothesis. However, taking into account population priors, selection effects, and the prior odds against lensing, these events do not provide sufficient evidence for lensing. Overall, we find no compelling evidence for lensing in the observed gravitational-wave signals from any of these analyses.
Searches for Continuous Gravitational Waves from Young Supernova Remnants in the Early Third Observing Run of Advanced LIGO and Virgo

R. Abbott, T. D. Abbott, S. Abraham, and 1586 more authors

The Astrophysical Journal, Nov 2021

Abs

We present results of three wide-band directed searches for continuous gravitational waves from 15 young supernova remnants in the first half of the third Advanced LIGO and Virgo observing run. We use three search pipelines with distinct signal models and methods of identifying noise artifacts. Without ephemerides of these sources, the searches are conducted over a fRequency band spanning from 10 to 2 kHz. We find no evidence of continuous gravitational radiation from these sources. We set upper limits on the intrinsic signal strain at 95% confidence level in sample subbands, estimate the sensitivity in the full band, and derive the corresponding constraints on the fiducial neutron star ellipticity and r-mode amplitude. The best 95% confidence constraints placed on the signal strain are 7.7 × 10−26 and 7.8 × 10−26 near 200 Hz for the supernova remnants G39.2–0.3 and G65.7+1.2, respectively. The most stringent constraints on the ellipticity and r-mode amplitude reach ≲10−7 and ≲ 10−5, respectively, at frequencies above ∼400 Hz for the closest supernova remnant G266.2–1.2/Vela Jr.
Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo

Rich Abbott, Thomas D. Abbott, Sheelu Abraham, and 1244 more authors

SoftwareX, Nov 2021

Abs

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software.
A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 1188 more authors

The Astrophysical Journal, Mar 2021

Abs

This paper presents the gravitational-wave measurement of the Hubble constant (H 0) using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart of the binary neutron star GW170817 led to the first standard-siren measurement of H 0. Here we additionally use binary black hole detections in conjunction with galaxy catalogs and report a joint measurement. Our updated measurement is H 0 = km s−1 Mpc−1 (68.3% of the highest density posterior interval with a flat-in-log prior) which is an improvement by a factor of 1.04 (about 4%) over the GW170817-only value of km s−1 Mpc−1. A significant additional contribution currently comes from GW170814, a loud and well-localized detection from a part of the sky thoroughly covered by the Dark Energy Survey. With numerous detections anticipated over the upcoming years, an exhaustive understanding of other systematic effects are also going to become increasingly important. These results establish the path to cosmology using gravitational-wave observations with and without transient electromagnetic counterparts.
Observation of Gravitational Waves from Two Neutron Star–Black Hole Coalescences

R. Abbott, T. D. Abbott, S. Abraham, and 1598 more authors

The Astrophysical Journal Letters, Jun 2021

Abs

We report the observation of gravitational waves from two compact binary coalescences in LIGO’s and Virgo’s third observing run with properties consistent with neutron star–black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo and the second by all three LIGO–Virgo detectors. The source of GW200105 has component masses and , whereas the source of GW200115 has component masses and (all measurements quoted at the 90% credible level). The probability that the secondary’s mass is below the maximal mass of a neutron star is 89%–96% and 87%–98%, respectively, for GW200105 and GW200115, with the ranges arising from different astrophysical assumptions. The source luminosity distances are and , respectively. The magnitude of the primary spin of GW200105 is less than 0.23 at the 90% credible level, and its orientation is unconstrained. For GW200115, the primary spin has a negative spin projection onto the orbital angular momentum at 88% probability. We are unable to constrain the spin or tidal deformation of the secondary component for either event. We infer an NSBH merger rate density of when assuming that GW200105 and GW200115 are representative of the NSBH population or under the assumption of a broader distribution of component masses.
Laser power stabilization for Advanced VIRGO

Frédéric Cleva, Jean-Pierre Coulon, Li Wei Wei, and 5 more authors

In 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, Jun 2021

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We present the laser power stabilization in Advanced VIRGO using very high photocurrent photodiodes with excellent spatial uniformity. The RIN is currently 2.5E-9 Hz-12 and will be able to reach 1.2E-9 Hz-12 for the most sensitive configuration

2020

Optics mounting and alignment for the central optical bench of the dual cavity enhanced light-shining-through-a-wall experiment ALPS II

Li-Wei Wei, Kanioar Karan, and Benno Willke

Appl. Opt., Oct 2020

Abs

Any Light Particle Search II (ALPS II) is a light-shining-through-a-wall experiment seeking axion-like particles. ALPS II will feature two 120 m long linear optical cavities that are separated by a wall and support the same photon mode. The central optical bench at the core of the experiment will be equipped with a light-tight shutter and two planar mirrors for the cavities. We show that the mounting concept for ALPS II provides sufficient angular stability and verify that a simple autocollimator assisted alignment procedure for crucial components of the ALPS II optical cavities can lead to the required overlap of the cavity eigenmodes. Furthermore, we show that mounted quadrant photodiodes added to the optical bench can have sufficient stability to maintain this overlap even without a clear line of sight between the two optical cavities.
Prospects for improving the sensitivity of the cryogenic gravitational wave detector KAGRA

Yuta Michimura, Kentaro Komori, Yutaro Enomoto, and 18 more authors

Phys. Rev. D, Jul 2020
GW190521: A Binary Black Hole Merger with a Total Mass of 150\text \text M_\ensuremath\bigodot

R. Abbott, T. D. Abbott, S. Abraham, and 1253 more authors

Phys. Rev. Lett., Sep 2020
GW190425: Observation of a Compact Binary Coalescence with Total Mass ∼ 3.4 M⊙

B. P. Abbott, R. Abbott, T. D. Abbott, and 1197 more authors

The Astrophysical Journal Letters, Mar 2020

Abs

On 2019 April 25, the LIGO Livingston detector observed a compact binary coalescence with signal-to-noise ratio 12.9. The Virgo detector was also taking data that did not contribute to detection due to a low signal-to-noise ratio, but were used for subsequent parameter estimation. The 90% credible intervals for the component masses range from to (– if we restrict the dimensionless component spin magnitudes to be smaller than 0.05). These mass parameters are consistent with the individual binary components being neutron stars. However, both the source-frame chirp mass and the total mass of this system are significantly larger than those of any other known binary neutron star (BNS) system. The possibility that one or both binary components of the system are black holes cannot be ruled out from gravitational-wave data. We discuss possible origins of the system based on its inconsistency with the known Galactic BNS population. Under the assumption that the signal was produced by a BNS coalescence, the local rate of neutron star mergers is updated to 250–2810 .
Properties and Astrophysical Implications of the 150\text \text M_\ensuremath\bigodot Binary Black Hole Merger GW190521

R. Abbott, T. D. Abbott, S. Abraham, and 1253 more authors

The Astrophysical Journal Letters, Sep 2020

Abs

The gravitational-wave signal GW190521 is consistent with a binary black hole (BBH) merger source at redshift 0.8 with unusually high component masses, M⊙ and M⊙, compared to previously reported events, and shows mild evidence for spin-induced orbital precession. The primary falls in the mass gap predicted by (pulsational) pair-instability supernova theory, in the approximate range 65–120 M⊙. The probability that at least one of the black holes in GW190521 is in that range is 99.0%. The final mass of the merger ( M⊙) classifies it as an intermediate-mass black hole. Under the assumption of a quasi-circular BBH coalescence, we detail the physical properties of GW190521’s source binary and its post-merger remnant, including component masses and spin vectors. Three different waveform models, as well as direct comparison to numerical solutions of general relativity, yield consistent estimates of these properties. Tests of strong-field general relativity targeting the merger-ringdown stages of the coalescence indicate consistency of the observed signal with theoretical predictions. We estimate the merger rate of similar systems to be . We discuss the astrophysical implications of GW190521 for stellar collapse and for the possible formation of black holes in the pair-instability mass gap through various channels: via (multiple) stellar coalescences, or via hierarchical mergers of lower-mass black holes in star clusters or in active galactic nuclei. We find it to be unlikely that GW190521 is a strongly lensed signal of a lower-mass black hole binary merger. We also discuss more exotic possible sources for GW190521, including a highly eccentric black hole binary, or a primordial black hole binary.
GW190412: Observation of a binary-black-hole coalescence with asymmetric masses

R. Abbott, T. D. Abbott, S. Abraham, and 1252 more authors

Phys. Rev. D, Aug 2020
Optically targeted search for gravitational waves emitted by core-collapse supernovae during the first and second observing runs of advanced LIGO and advanced Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 1192 more authors

Phys. Rev. D, Apr 2020
A Joint Fermi-GBM and LIGO/Virgo Analysis of Compact Binary Mergers from the First and Second Gravitational-wave Observing Runs

R. Hamburg, C. Fletcher, E. Burns, and 1262 more authors

The Astrophysical Journal, Apr 2020

Abs

We present results from offline searches of Fermi Gamma-ray Burst Monitor (GBM) data for gamma-ray transients coincident with the compact binary coalescences observed by the gravitational-wave (GW) detectors Advanced LIGO and Advanced Virgo during their first and second observing runs. In particular, we perform follow-up for both confirmed events and low significance candidates reported in the LIGO/Virgo catalog GWTC-1. We search for temporal coincidences between these GW signals and GBM-triggered gamma-ray bursts (GRBs). We also use the GBM Untargeted and Targeted subthreshold searches to find coincident gamma-rays below the onboard triggering threshold. This work implements a refined statistical approach by incorporating GW astrophysical source probabilities and GBM visibilities of LIGO/Virgo sky localizations to search for cumulative signatures of coincident subthreshold gamma-rays. All search methods recover the short gamma-ray burst GRB 170817A occurring ∼1.7 s after the binary neutron-star merger GW170817. We also present results from a new search seeking GBM counterparts to LIGO single-interferometer triggers. This search finds a candidate joint event, but given the nature of the GBM signal and localization, as well as the high joint false alarm rate of 1.1 × 10−6 Hz, we do not consider it an astrophysical association. We find no additional coincidences.
Model comparison from LIGO–Virgo data on GW170817’s binary components and consequences for the merger remnant

B P Abbott, R Abbott, T D Abbott, and 1191 more authors

Classical and Quantum Gravity, Jan 2020

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GW170817 is the very first observation of gravitational waves originating from the coalescence of two compact objects in the mass range of neutron stars, accompanied by electromagnetic counterparts, and offers an opportunity to directly probe the internal structure of neutron stars. We perform Bayesian model selection on a wide range of theoretical predictions for the neutron star equation of state. For the binary neutron star hypothesis, we find that we cannot rule out the majority of theoretical models considered. In addition, the gravitational-wave data alone does not rule out the possibility that one or both objects were low-mass black holes. We discuss the possible outcomes in the case of a binary neutron star merger, finding that all scenarios from prompt collapse to long-lived or even stable remnants are possible. For long-lived remnants, we place an upper limit of 1.9 kHz on the rotation rate. If a black hole was formed any time after merger and the coalescing stars were slowly rotating, then the maximum baryonic mass of non-rotating neutron stars is at most , and three equations of state considered here can be ruled out. We obtain a tighter limit of for the case that the merger results in a hypermassive neutron star.
A guide to LIGO–Virgo detector noise and extraction of transient gravitational-wave signals

B P Abbott, R Abbott, T D Abbott, and 1135 more authors

Classical and Quantum Gravity, Feb 2020

Abs

The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitational-wave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data and methods used in the analyses. In this paper, we provide an overview of the detector noise properties and the data analysis techniques used to detect gravitational-wave signals and infer the source properties. We describe some of the checks that are performed to validate the analyses and results from the observations of gravitational-wave events. We also address concerns that have been raised about various properties of LIGO–Virgo detector noise and the correctness of our analyses as applied to the resulting data.
GW190814: Gravitational Waves from the Coalescence of a 23 Solar Mass Black Hole with a 2.6 Solar Mass Compact Object

R. Abbott, T. D. Abbott, S. Abraham, and 1254 more authors

The Astrophysical Journal Letters, Jun 2020

Abs

We report the observation of a compact binary coalescence involving a 22.2–24.3 M⊙ black hole and a compact object with a mass of 2.50–2.67 M⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, , and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to ≤0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries.
Gravitational-wave Constraints on the Equatorial Ellipticity of Millisecond Pulsars

R. Abbott, T. D. Abbott, S. Abraham, and 1335 more authors

The Astrophysical Journal Letters, Oct 2020

Abs

We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437−4715, PSR J0711−6830, and PSR J0737−3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835−4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time, we are able to match (for PSR J0437−4715) or surpass (for PSR J0711−6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and constrain their equatorial ellipticities to be less than 10−8. For each of the five pulsars, we perform targeted searches that assume a tight coupling between the gravitational-wave and electromagnetic signal phase evolution. We also present constraints on PSR J0711−6830, the Crab pulsar, and the Vela pulsar from a search that relaxes this assumption, allowing the gravitational-wave signal to vary from the electromagnetic expectation within a narrow band of frequencies and frequency derivatives.
Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

B. P. Abbott, R. Abbott, T. D. Abbott, and 297 more authors

Living Reviews in Relativity, Sep 2020

2019

Search for Subsolar Mass Ultracompact Binaries in Advanced LIGO’s Second Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1185 more authors

Phys. Rev. Lett., Oct 2019
Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network

B. P. Abbott, R. Abbott, T. D. Abbott, and 1194 more authors

Phys. Rev. D, Sep 2019
Tests of general relativity with the binary black hole signals from the LIGO-Virgo catalog GWTC-1

B. P. Abbott, R. Abbott, T. D. Abbott, and 1140 more authors

Phys. Rev. D, Nov 2019
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

B. P. Abbott, R. Abbott, T. D. Abbott, and 1132 more authors

Phys. Rev. D, Dec 2019
Search for Eccentric Binary Black Hole Mergers with Advanced LIGO and Advanced Virgo during Their First and Second Observing Runs

B. P. Abbott, R. Abbott, T. D. Abbott, and 1183 more authors

The Astrophysical Journal, Sep 2019

Abs

When formed through dynamical interactions, stellar-mass binary black holes (BBHs) may retain eccentric orbits (e > 0.1 at 10 Hz) detectable by ground-based gravitational-wave detectors. Eccentricity can therefore be used to differentiate dynamically formed binaries from isolated BBH mergers. Current template-based gravitational-wave 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 ≳100 Gpc−3 yr−1 for e > 0.1, assuming a black hole mass spectrum with a power-law index ≲2.
Search for Gravitational-wave Signals Associated with Gamma-Ray Bursts during the Second Observing Run of Advanced LIGO and Advanced Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 1196 more authors

The Astrophysical Journal, Nov 2019

Abs

We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38 × 10−6 (modeled) and 3.1 × 10−4 (unmodeled). We do not find any significant evidence for gravitational-wave signals associated with the other gamma-ray bursts analyzed, and therefore we report lower bounds on the distance to each of these, assuming various source types and signal morphologies. Using our final modeled search results, short gamma-ray burst observations, and assuming binary neutron star progenitors, we place bounds on the rate of short gamma-ray bursts as a function of redshift for z ≤ 1. We estimate 0.07–1.80 joint detections with Fermi-GBM per year for the 2019–20 LIGO-Virgo observing run and 0.15–3.90 per year when current gravitational-wave detectors are operating at their design sensitivities.
Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 1139 more authors

The Astrophysical Journal Letters, Sep 2019

Abs

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 and a power-law index of α = (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 = 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.
Searches for Continuous Gravitational Waves from 15 Supernova Remnants and Fomalhaut b with Advanced LIGO*

B. P. Abbott, R. Abbott, T. D. Abbott, and 1130 more authors

The Astrophysical Journal, Apr 2019

Abs

We describe directed searches for continuous gravitational waves (GWs) from 16 well-localized 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 3.5–53.7 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 × 10−25, fiducial neutron star ellipticity as strict as 2 × 10−9, and fiducial r-mode amplitude as strict as 3 × 10−8.
Search for the isotropic stochastic background using data from Advanced LIGO’s second observing run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1131 more authors

Phys. Rev. D, Sep 2019
Directional limits on persistent gravitational waves using data from Advanced LIGO’s first two observing runs

B. P. Abbott, R. Abbott, T. D. Abbott, and 1130 more authors

Phys. Rev. D, Sep 2019
GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs

B. P. Abbott, R. Abbott, T. D. Abbott, and 1146 more authors

Phys. Rev. X, Sep 2019
All-sky search for short gravitational-wave bursts in the second Advanced LIGO and Advanced Virgo run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1184 more authors

Phys. Rev. D, Jul 2019
All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO O2 data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1137 more authors

Phys. Rev. D, Jul 2019
Tests of General Relativity with GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1143 more authors

Phys. Rev. Lett., Jul 2019
Narrow-band search for gravitational waves from known pulsars using the second LIGO observing run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1133 more authors

Phys. Rev. D, Jun 2019
Searches for Gravitational Waves from Known Pulsars at Two Harmonics in 2015–2017 LIGO Data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1149 more authors

The Astrophysical Journal, Jun 2019

Abs

We present a search for gravitational waves from 222 pulsars with rotation frequencies ?10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015¡V2017, which provides the highest-sensitivity gravitational-wave 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¡¦s rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search, we provide updated upper limits on the gravitational-wave 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¡¦ spin-down. For the Crab and Vela pulsars our results constrain gravitational-wave emission to account for less than 0.017% and 0.18% of the spin-down luminosity, respectively. For the recycled millisecond pulsar J0711?6830 our limits are only a factor of 1.3 above the spin-down limit, assuming the canonical value of 1038 kg m2 for the star¡¦s moment of inertia, and imply a gravitational-wave-derived upper limit on the star¡¦s ellipticity of 1.2 ¡Ѡ10?8. We also place new limits on the emission amplitude at the rotation frequency of the pulsars.
All-sky search for long-duration gravitational-wave transients in the second Advanced LIGO observing run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1181 more authors

Phys. Rev. D, May 2019
First Measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary–Black-hole Merger GW170814

M. Soares-Santos, A. Palmese, W. Hartley, and 1200 more authors

The Astrophysical Journal, Apr 2019

Abs

We present a multi-messenger measurement of the Hubble constant H0 using the binary¡Vblack-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s?1 Mpc?1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s?1 Mpc?1, we find (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H0.
Search for Gravitational Waves from a Long-lived Remnant of the Binary Neutron Star Merger GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1137 more authors

The Astrophysical Journal, Apr 2019

Abs

One unanswered question about the binary neutron star coalescence GW170817 is the nature of its post-merger remnant. A previous search for post-merger 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 LIGO-Virgo observing run, which was 8.5 days after the coalescence of GW170817. The main physical scenario for this emission is the power-law spindown of a massive magnetar-like 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 post-merger analyses in future observing runs with expected higher sensitivity.
Low-latency Gravitational-wave Alerts for Multimessenger Astronomy during the Second Advanced LIGO and Virgo Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1129 more authors

The Astrophysical Journal, Apr 2019

Abs

Advanced LIGO¡¦s second observing run (O2), conducted from 2016 November 30 to 2017 August 25, combined with Advanced Virgo¡¦s first observations in 2017 August, witnessed the birth of gravitational-wave multimessenger astronomy. The first ever gravitational-wave detection from the coalescence of two neutron stars, GW170817, and its gamma-ray counterpart, GRB 170817A, led to an electromagnetic follow-up 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, X-ray, and radio counterparts. In this article, we describe the online identification of gravitational-wave transients and the distribution of gravitational-wave 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 gravitational-wave 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.
Search for Transient Gravitational-wave Signals Associated with Magnetar Bursts during Advanced LIGO’s Second Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1127 more authors

The Astrophysical Journal, Apr 2019

Abs

We present the results of a search for short- and intermediate-duration gravitational-wave signals from four magnetar bursts in Advanced LIGO¡¦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 (hrss) from incoming intermediate-duration gravitational waves ranging from 1.1 ¡Ѡ10?22 at 150 Hz to 4.4 ¡Ѡ10?22 at 1550 Hz at 50% detection efficiency. From the known distance to the magnetar SGR 1806¡V20 (8.7 kpc), we can place upper bounds on the isotropic gravitational-wave energy of 3.4 ¡Ѡ1044 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¡¦s sixth science run. The short-duration search yielded upper limits of 2.1 ¡Ѡ1044 erg for short white noise bursts, and 2.3 ¡Ѡ1047 erg for 100 ms long ringdowns at 1500 Hz, both at 50% detection efficiency.
Constraining the p-Mode–g-Mode Tidal Instability with GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1136 more authors

Phys. Rev. Lett., Feb 2019
A Fermi Gamma-Ray Burst Monitor Search for Electromagnetic Signals Coincident with Gravitational-wave Candidates in Advanced LIGO’s First Observing Run

E. Burns, A. Goldstein, C. M. Hui, and 1159 more authors

The Astrophysical Journal, Jan 2019

Abs

We present a search for prompt gamma-ray counterparts to compact binary coalescence gravitational wave (GW) candidates from Advanced LIGO¡¦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 low-significance GW candidates from the O1 compact binary coalescence searches using the Fermi Gamma-Ray 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 gamma-ray follow-up. No GW candidates were found to be coincident with gamma-ray 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 gamma-ray transient GW150914-GBM presented in Connaughton et al. and a solar flare in chance coincidence with a GW candidate.
Search for Multimessenger Sources of Gravitational Waves and High-energy Neutrinos with Advanced LIGO during Its First Observing Run, ANTARES, and IceCube

A. Albert, M. André, M. Anghinolfi, and 1588 more authors

The Astrophysical Journal, Jan 2019

Abs

Astrophysical sources of gravitational waves, such as binary neutron star and black hole mergers or core-collapse supernovae, can drive relativistic outflows, giving rise to non-thermal high-energy emission. High-energy neutrinos are signatures of such outflows. The detection of gravitational waves and high-energy 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 high-energy 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 gravitational-wave and neutrino emission processes.
Properties of the Binary Neutron Star Merger GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1145 more authors

Phys. Rev. X, Jan 2019

2018

First Search for Nontensorial Gravitational Waves from Known Pulsars

B. P. Abbott, R. Abbott, T. D. Abbott, and 1049 more authors

Phys. Rev. Lett., Jan 2018
GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences

B. P. Abbott, R. Abbott, T. D. Abbott, and 1097 more authors

Phys. Rev. Lett., Feb 2018
Effects of data quality vetoes on a search for compact binary coalescences in Advanced LIGO’s first observing run

B P Abbott, R Abbott, T D Abbott, and 957 more authors

Classical and Quantum Gravity, Feb 2018

Abs

The first observing run of Advanced LIGO spanned 4 months, from 12 September 2015 to 19 January 2016, during which gravitational waves were directly detected from two binary black hole systems, namely GW150914 and GW151226. Confident detection of gravitational waves requires an understanding of instrumental transients and artifacts that can reduce the sensitivity of a search. Studies of the quality of the detector data yield insights into the cause of instrumental artifacts and data quality vetoes specific to a search are produced to mitigate the effects of problematic data. In this paper, the systematic removal of noisy data from analysis time is shown to improve the sensitivity of searches for compact binary coalescences. The output of the PyCBC pipeline, which is a python-based code package used to search for gravitational wave signals from compact binary coalescences, is used as a metric for improvement. GW150914 was a loud enough signal that removing noisy data did not improve its significance. However, the removal of data with excess noise decreased the false alarm rate of GW151226 by more than two orders of magnitude, from 1 in 770 yr to less than 1 in 186 000 yr.
Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

B. P. Abbott, R. Abbott, T. D. Abbott, and 297 more authors

Living Reviews in Relativity, Apr 2018

Abs

We present possible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave 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\backslash%}}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 5–}}20~\backslashmathrm {deg}^2}}requires at least three detectors of sensitivity within a factor of }}\backslashsim 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 gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
Search for Subsolar-Mass Ultracompact Binaries in Advanced LIGO’s First Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1135 more authors

Phys. Rev. Lett., Dec 2018
GW170817: Measurements of Neutron Star Radii and Equation of State

B. P. Abbott, R. Abbott, T. D. Abbott, and 1147 more authors

Phys. Rev. Lett., Oct 2018
Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

B. P. Abbott, R. Abbott, T. D. Abbott, and 1096 more authors

Phys. Rev. Lett., May 2018
Full band all-sky search for periodic gravitational waves in the O1 LIGO data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1097 more authors

Phys. Rev. D, May 2018
Constraints on cosmic strings using data from the first Advanced LIGO observing run

B. P. Abbott, R. Abbott, T. D. Abbott, and 1040 more authors

Phys. Rev. D, May 2018
All-sky search for long-duration gravitational wave transients in the first Advanced LIGO observing run

B P Abbott, R Abbott, T D Abbott, and 986 more authors

Classical and Quantum Gravity, Feb 2018

Abs

We present the results of a search for long-duration gravitational wave transients in the data of the LIGO Hanford and LIGO Livingston second generation detectors between and , with a total observational time of . The search targets gravitational wave transients of 10¡V500?s duration in a frequency band of 24¡V2048 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 long-duration 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 in gravitational waves.

2017

First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1037 more authors

Phys. Rev. D, Dec 2017
Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1100 more authors

The Astrophysical Journal Letters, Dec 2017

Abs

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-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 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 r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if ≳10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.
On the Progenitor of Binary Neutron Star Merger GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1095 more authors

The Astrophysical Journal Letters, Dec 2017

Abs

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy’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 three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick 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’s star formation history, provided the stellar populations are older than 1 Gyr.
Search for High-energy Neutrinos from Binary Neutron Star Merger GW170817 with ANTARES, IceCube, and the Pierre Auger Observatory

A. Albert, M. André, M. Anghinolfi, and 1942 more authors

The Astrophysical Journal Letters, Nov 2017

Abs

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray 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 high-energy neutrinos from the merger in the GeV–EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident with the source were detected within ±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 high-energy 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 non-detection is consistent with model predictions of short GRBs observed at a large off-axis angle.
GW170608: Observation of a 19 Solar-mass Binary Black Hole Coalescence

B. P. Abbott, R. Abbott, T. D. Abbott, and 1099 more authors

The Astrophysical Journal, Dec 2017

Abs

On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave (GW) signal from the merger of two stellar-mass black holes was observed by the two Advanced Laser Interferometer Gravitational-Wave Observatory detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses of and (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through GWs with electromagnetic observations. The source¡¦s luminosity distance is , corresponding to redshift . We verify that the signal waveform is consistent with the predictions of general relativity.
Search for Post-merger Gravitational Waves from the Remnant of the Binary Neutron Star Merger GW170817

B. P. Abbott, R. Abbott, T. D. Abbott, and 1103 more authors

The Astrophysical Journal, Dec 2017

Abs

The first observation of a binary neutron star (NS) coalescence by the Advanced LIGO and Advanced Virgo gravitational-wave (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 long-lived 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- (?1 s) and intermediate-duration (?500 s) signals, which include GW emission from a hypermassive NS or supramassive NS, respectively. We find no signal from the post-merger 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 1¡V4 kHz is at 50% detection efficiency. For intermediate-duration signals, our best upper limit at 50% detection efficiency is for a millisecond magnetar model, and for a bar-mode model. These results indicate that post-merger emission from a similar event may be detectable when advanced detectors reach design sensitivity or with next-generation detectors.
A gravitational-wave standard siren measurement of the Hubble constant

Nature, Nov 2017

Abs

The astronomical event GW170817, detected in gravitational and electromagnetic waves, is used to determine the expansion rate of the Universe, which is consistent with and independent of existing measurements.
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A

B. P. Abbott, R. Abbott, T. D. Abbott, and 1153 more authors

The Astrophysical Journal Letters, Oct 2017

Abs

On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is . 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 between GRB 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between and 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 gamma-rays. 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 gamma-ray 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 Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1–1.4 per year during the 2018–2019 observing run and 0.3–1.7 per year at design sensitivity.
GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral

B. P. Abbott, R. Abbott, T. D. Abbott, and 1121 more authors

Phys. Rev. Lett., Oct 2017
GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence

B. P. Abbott, R. Abbott, T. D. Abbott, and 1105 more authors

Phys. Rev. Lett., Oct 2017
Multi-messenger Observations of a Binary Neutron Star Merger*

The Astrophysical Journal Letters, Oct 2017

Abs

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 Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 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 . 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 ) less than 11 hours after the merger by the One-Meter, 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 non-detections, X-ray and radio emission were discovered at the transient’s position and days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1046 more authors

The Astrophysical Journal, Sep 2017

Abs

We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, 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 25–, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and simulated signal injections. The most stringent upper limit was set at , with comparable limits set across the most sensitive frequency range from 100 to . At this frequency, the 95% upper limit on the signal amplitude h0 is marginalized over the unknown inclination angle of the neutron star’s spin, and assuming the best orientation (which results in circularly polarized gravitational waves). These limits are a factor of 3–4 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 , 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° is assumed, they are within a factor of 1.7.
All-sky search for periodic gravitational waves in the O1 LIGO data

B. P. Abbott, R. Abbott, T. D. Abbott, and 1044 more authors

Phys. Rev. D, Sep 2017
Effects of waveform model systematics on the interpretation of GW150914

B P Abbott, R Abbott, T D Abbott, and 998 more authors

Classical and Quantum Gravity, Apr 2017

Abs

Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic 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¡¦s equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space 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 edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than???0.05. For signals with higher signal-to-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 gravitational-wave measurements, making more accurate models desirable for future observations.
Exploring the sensitivity of next generation gravitational wave detectors

B P Abbott, R Abbott, T D Abbott, and 720 more authors

Classical and Quantum Gravity, Jan 2017

Abs

The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.
First Search for Gravitational Waves from Known Pulsars with Advanced LIGO

B. P. Abbott, R. Abbott, T. D. Abbott, and 1003 more authors

The Astrophysical Journal, Apr 2017

Abs

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 gravitational-wave signal from any of these pulsars, but we are able to set the most constraining upper limits yet on their gravitational-wave amplitudes and ellipticities. For eight of these pulsars, our upper limits give bounds that are improvements over the indirect spin-down limit values. For another 32, we are within a factor of 10 of the spin-down 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.
Search for Gravitational Waves Associated with Gamma-Ray Bursts during the First Advanced LIGO Observing Run and Implications for the Origin of GRB 150906B

B. P. Abbott, R. Abbott, T. D. Abbott, and 1003 more authors

The Astrophysical Journal, May 2017

Abs

We present the results of the search for gravitational waves (GWs) associated with £^ -ray bursts detected during the first observing run of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). We find no evidence of a GW signal for any of the 41 £^ -ray bursts for which LIGO data are available with sufficient duration. For all £^ -ray bursts, we place lower bounds on the distance to the source using the optimistic assumption that GWs with an energy of ##IMG## [http://ej.iop.org/images/0004-637X/841/2/89/apjaa6c47ieqn1.gif] 10^-2M_⊙c^2 were emitted within the ##IMG## [http://ej.iop.org/images/0004-637X/841/2/89/apjaa6c47ieqn2.gif] 16 ¡V ##IMG## [http://ej.iop.org/images/0004-637X/841/2/89/apjaa6c47ieqn3.gif] 500 Hz band, and we find a median 90% confidence limit of 71 Mpc at 150 Hz. For the subset of 19 short/hard £^ -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 star¡Vblack 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 ##IMG## [http://ej.iop.org/images/0004-637X/841/2/89/apjaa6c47ieqn4.gif] 54 Mpc ( z = 0.0124). Assuming the £^ -ray emission is beamed with a jet half-opening angle ##IMG## [http://ej.iop.org/images/0004-637X/841/2/89/apjaa6c47ieqn5.gif] \leqslant 30^∘ , we exclude a BNS and a neutron star¡Vblack 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.
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

B. P. Abbott, R. Abbott, T. D. Abbott, and 1038 more authors

Phys. Rev. D, Jul 2017
Search for high-energy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube

A. Albert, M. André, M. Anghinolfi, and 1413 more authors

Phys. Rev. D, Jul 2017
GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

B. P. Abbott, R. Abbott, T. D. Abbott, and 1046 more authors

Phys. Rev. Lett., Jun 2017
Search for gravitational waves from Scorpius X-1 in the first Advanced LIGO observing run with a hidden Markov model

B. P. Abbott, R. Abbott, T. D. Abbott, and 1041 more authors

Phys. Rev. D, Jun 2017
Search for continuous gravitational waves from neutron stars in globular cluster NGC 6544

B. P. Abbott, R. Abbott, T. D. Abbott, and 953 more authors

Phys. Rev. D, Apr 2017
Upper Limits on the Stochastic Gravitational-Wave Background from Advanced LIGO’s First Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 992 more authors

Phys. Rev. Lett., Mar 2017
Directional Limits on Persistent Gravitational Waves from Advanced LIGO’s First Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 993 more authors

Phys. Rev. Lett., Mar 2017
All-sky search for short gravitational-wave bursts in the first Advanced LIGO run

B. P. Abbott, R. Abbott, T. D. Abbott, and 983 more authors

Phys. Rev. D, Feb 2017

2016

Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo

B. P. Abbott, R. Abbott, T. D. Abbott, and 297 more authors

Living Reviews in Relativity, Feb 2016

Abs

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising 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 5 deg2 to 20 deg2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
The basic physics of the binary black hole merger GW150914

LIGO Scientific, VIRGO Collaborations, B. P. Abbott, and 954 more authors

Annalen der Physik, Oct 2016

1600209
Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914

B P Abbott, R Abbott, T D Abbott, and 963 more authors

Classical and Quantum Gravity, Jun 2016

Abs

On 14 September 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.
The Rate of Binary Black Hole Mergers Inferred from Advanced LIGO Observations Surrounding GW150914

B. P. Abbott, R. Abbott, T. D. Abbott, and 964 more authors

The Astrophysical Journal Letters, Nov 2016

Abs

A transient gravitational-wave signal, GW150914, was identified in the twin Advanced LIGO detectors on 2015 September 2015 at 09:50:45 UTC. To assess the implications of this discovery, the detectors remained in operation with unchanged configurations over a period of 39 days around the time of the signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate (FAR) of ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn1.gif] \lt 4.9\times 10^-6\,\mathrmyr^-1 , yielding a p -value for GW150914 of ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn2.gif] \lt 2\times 10^-7 . Parameter estimation follow-up on this trigger identifies its source as a binary black hole (BBH) merger with component masses ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn3.gif] (m_1,m_2)=(36_-4^+5,29_-4^+4)\,M_⊙ at redshift ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn4.gif] z=0.09_-0.04^+0.03 (median and 90% credible range). Here, we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn5.gif] 2\mbox–53\,\mathrmGpc^-3\,\mathrmyr^-1 (comoving frame). Incorporating all search triggers that pass a much lower threshold while accounting for the uncertainty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn6.gif] 13\mbox–600\,\mathrmGpc^-3\,\mathrmyr^-1 depending on assumptions about the BBH mass distribution. All together, our various rate estimates fall in the conservative range ##IMG## [http://ej.iop.org/images/2041-8205/833/1/L1/apjlaa4677ieqn7.gif] 2\mbox–600\,\mathrmGpc^-3\,\mathrmyr^-1 .
Upper Limits on the Rates of Binary Neutron Star and Neutron Star-Black Hole Mergers from Advanced LIGO’s First Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 957 more authors

The Astrophysical Journal Letters, Nov 2016

Abs

We report here the non-detection of gravitational waves from the merger of binary¡Vneutron star systems and neutron star¡Vblack hole systems during the first observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). In particular, we searched for gravitational-wave signals from binary¡Vneutron star systems with component masses ##IMG## [http://ej.iop.org/images/2041-8205/832/2/L21/apjlaa47c3ieqn1.gif] ∈[1,3]\,M_⊙ and component dimensionless spins <0.05. We also searched for neutron star¡Vblack hole systems with the same neutron star parameters, black hole mass ##IMG## [http://ej.iop.org/images/2041-8205/832/2/L21/apjlaa47c3ieqn2.gif] ∈[2,99]\,M_⊙ , and no restriction on the black hole spin magnitude. We assess the sensitivity of the two LIGO detectors to these systems and find that they could have detected the merger of binary¡Vneutron star systems with component mass distributions of 1.35 ¡Ӡ0.13 M ¡󠡴 a volume-weighted average distance of ?70 Mpc, and for neutron star¡Vblack hole systems with neutron star masses of 1.4 M ¡󠡮d black hole masses of at least 5 M ¡󠬠a volume-weighted average distance of at least ?110 Mpc. From this we constrain with 90% confidence the merger rate to be less than 12,600 Gpc ?3 yr ?1 for binary¡Vneutron star systems and less than 3600 Gpc ?3 yr ?1 for neutron star¡Vblack hole systems. We discuss the astrophysical implications of these results, which we find to be in conflict with only the most optimistic predictions. However, we find that if no detection of neutron star¡Vbinary mergers is made in the next two Advanced LIGO and Advanced Virgo observing runs we would place significant constraints on the merger rates. Finally, assuming a rate of ##IMG## [http://ej.iop.org/images/2041-8205/832/2/L21/apjlaa47c3ieqn3.gif] 10_-7^+20 Gpc ?3 yr ?1 , short gamma-ray bursts beamed toward the Earth, and assuming that all short gamma-ray bursts have binary¡Vneutron star (neutron star¡Vblack hole) progenitors, we can use our 90% confidence rate upper limits to constrain the beaming angle of the gamma-ray burst to be greater than ##IMG## [http://ej.iop.org/images/2041-8205/832/2/L21/apjlaa47c3ieqn4.gif] 2\buildrel∘\over. 3_-1.1^+1.7 ( ##IMG## [http://ej.iop.org/images/2041-8205/832/2/L21/apjlaa47c3ieqn5.gif] 4\buildrel∘\over. 3_-1.9^+3.1 ).
Localization and Broadband Follow-up of the Gravitational-wave Transient GW150914

B. P. Abbott, R. Abbott, T. D. Abbott, and 1572 more authors

The Astrophysical Journal Letters, Jul 2016

Abs

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams.
Coherently combined master oscillator fiber power amplifiers for Advanced Virgo

Li-Wei Wei, Frédéric Cleva, and Catherine Nary Man

Opt. Lett., Dec 2016

Abs

Stable low-noise high-power lasers are indispensable in advancing the strain sensitivity of interferometric gravitational wave detectors. Advanced LIGO and Advanced Virgo are currently under commissioning and require about 200 W of single-frequency laser power, while the future detector design may require up to the order of 500 W. In this Letter, we present the design and, to the best of our knowledge, the first experimental demonstration of the laser system for Advanced Virgo that is based on coherently combined fiber laser amplifiers. We show the long-term performance of two 40 W fiber laser amplifiers, as well as their characterization in terms of beam quality, power noise, phase noise, and beam pointing. Moreover, a simple and compact setup utilizing fibered modulators and actuators for the coherent beam combination of these two fiber laser amplifiers is reported. A combination efficiency of about 96% was achieved, and no spurious noise was observed.
First targeted search for gravitational-wave bursts from core-collapse supernovae in data of first-generation laser interferometer detectors

B. P. Abbott, R. Abbott, T. D. Abbott, and 964 more authors

Phys. Rev. D, Nov 2016
Results of the deepest all-sky survey for continuous gravitational waves on LIGO S6 data running on the Einstein@Home volunteer distributed computing project

B. P. Abbott, R. Abbott, T. D. Abbott, and 953 more authors

Phys. Rev. D, Nov 2016
Improved Analysis of GW150914 Using a Fully Spin-Precessing Waveform Model

B. P. Abbott, R. Abbott, T. D. Abbott, and 986 more authors

Phys. Rev. X, Oct 2016
Binary Black Hole Mergers in the First Advanced LIGO Observing Run

B. P. Abbott, R. Abbott, T. D. Abbott, and 970 more authors

Phys. Rev. X, Oct 2016
Directly comparing GW150914 with numerical solutions of Einstein’s equations for binary black hole coalescence

B. P. Abbott, R. Abbott, T. D. Abbott, and 974 more authors

Phys. Rev. D, Sep 2016
Comprehensive all-sky search for periodic gravitational waves in the sixth science run LIGO data

B. P. Abbott, R. Abbott, T. D. Abbott, and 957 more authors

Phys. Rev. D, Aug 2016
GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

B. P. Abbott, R. Abbott, T. D. Abbott, and 977 more authors

Phys. Rev. D, Jun 2016
GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

B. P. Abbott, R. Abbott, T. D. Abbott, and 974 more authors

Phys. Rev. Lett., Jun 2016
Observing gravitational-wave transient GW150914 with minimal assumptions

B. P. Abbott, R. Abbott, T. D. Abbott, and 966 more authors

Phys. Rev. D, Jun 2016
Properties of the Binary Black Hole Merger GW150914

B. P. Abbott, R. Abbott, T. D. Abbott, and 985 more authors

Phys. Rev. Lett., Jun 2016
Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

B. P. Abbott, R. Abbott, T. D. Abbott, and 995 more authors

Phys. Rev. D, Jun 2016
High-energy neutrino follow-up search of gravitational wave event GW150914 with ANTARES and IceCube

S. Adrián-Martı́nez, A. Albert, M. André, and 1397 more authors

Phys. Rev. D, Jun 2016
Tests of General Relativity with GW150914

B. P. Abbott, R. Abbott, T. D. Abbott, and 977 more authors

Phys. Rev. Lett., May 2016
GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

B. P. Abbott, R. Abbott, T. D. Abbott, and 954 more authors

Phys. Rev. Lett., Mar 2016
GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

B. P. Abbott, R. Abbott, T. D. Abbott, and 956 more authors

Phys. Rev. Lett., Mar 2016
First low frequency all-sky search for continuous gravitational wave signals

J. Aasi, B. P. Abbott, R. Abbott, and 919 more authors

Phys. Rev. D, Feb 2016
Search of the Orion spur for continuous gravitational waves using a loosely coherent algorithm on data from LIGO interferometers

J. Aasi, B. P. Abbott, R. Abbott, and 918 more authors

Phys. Rev. D, Feb 2016
All-sky search for long-duration gravitational wave transients with initial LIGO

B. P. Abbott, R. Abbott, T. D. Abbott, and 933 more authors

Phys. Rev. D, Feb 2016
Observation of Gravitational Waves from a Binary Black Hole Merger

B. P. Abbott, R. Abbott, T. D. Abbott, and 1008 more authors

Phys. Rev. Lett., Feb 2016
Astrophysical Implications of the Binary Black-hole Merger GW150914

B. P. Abbott, R. Abbott, T. D. Abbott, and 962 more authors

The Astrophysical Journal Letters, Feb 2016

Abs

The discovery of the gravitational-wave (GW) source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black hole (BH) systems that inspiral and merge within the age of the universe. Such BH mergers have been predicted in two main types of formation models, involving isolated binaries in galactic fields or dynamical interactions in young and old dense stellar environments. The measured masses robustly demonstrate that relatively ¡§heavy¡¨ BHs ( ##IMG## [http://ej.iop.org/images/2041-8205/818/2/L22/apjl522793ieqn1.gif] ≳25 ##IMG## [http://ej.iop.org/images/2041-8205/818/2/L22/apjl522793ieqn2.gif] M_⊙ ) can form in nature. This discovery implies relatively weak massive-star winds and thus the formation of GW150914 in an environment with a metallicity lower than about 1/2 of the solar value. The rate of binary-BH (BBH) mergers inferred from the observation of GW150914 is consistent with the higher end of rate predictions ( ##IMG## [http://ej.iop.org/images/2041-8205/818/2/L22/apjl522793ieqn3.gif] ≳1 Gpc ?3 yr ?1 ) from both types of formation models. The low measured redshift ( ##IMG## [http://ej.iop.org/images/2041-8205/818/2/L22/apjl522793ieqn4.gif] z≃0.1 ) of GW150914 and the low inferred metallicity of the stellar progenitor imply either BBH formation in a low-mass galaxy in the local universe and a prompt merger, or formation at high redshift with a time delay between formation and merger of several Gyr. This discovery motivates further studies of binary-BH formation astrophysics. It also has implications for future detections and studies by Advanced LIGO and Advanced Virgo, and GW detectors in space.

2015

Characterization of the LIGO detectors during their sixth science run

J Aasi, J Abadie, B P Abbott, and 867 more authors

Classical and Quantum Gravity, May 2015

Abs

In 2009¡V2010, the Laser Interferometer Gravitational-Wave Observatory (LIGO) operated together with international partners Virgo and GEO600 as a network to search for gravitational waves (GWs) of astrophysical origin. The sensitivity of these detectors was limited by a combination of noise sources inherent to the instrumental design and its environment, often localized in time or frequency, that couple into the GW readout. Here we review the performance of the LIGO instruments during this epoch, the work done to characterize the detectors and their data, and the effect that transient and continuous noise artefacts have on the sensitivity of LIGO to a variety of astrophysical sources.
Searches for Continuous Gravitational Waves from Nine Young Supernova Remnants

J. Aasi, B. P. Abbott, R. Abbott, and 891 more authors

The Astrophysical Journal, Oct 2015

Abs

We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target’s parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3¡V25.3 days using the matched-filtering ##IMG## [http://ej.iop.org/images/0004-637X/813/1/39/apj520467ieqn1.gif] \mathcalF -statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 ¡Ѡ10 ?25 on intrinsic strain, 2 ¡Ѡ10 ?7 on fiducial ellipticity, and 4 ¡Ѡ10 ?5 on r -mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r -mode amplitudes.
Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

J. Aasi, B. P. Abbott, R. Abbott, and 898 more authors

Phys. Rev. D, Mar 2015
Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data

J. Aasi, B. P. Abbott, R. Abbott, and 894 more authors

Phys. Rev. D, Jan 2015
Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

J. Aasi, J. Abadie, B. P. Abbott, and 872 more authors

Phys. Rev. D, Jan 2015

2014

Advanced Virgo: a second-generation interferometric gravitational wave detector

F Acernese, M Agathos, K Agatsuma, and 231 more authors

Classical and Quantum Gravity, Dec 2014

Abs

Advanced Virgo is the project to upgrade the Virgo interferometric detector of gravitational waves, with the aim of increasing the number of observable galaxies (and thus the detection rate) by three orders of magnitude. The project is now in an advanced construction phase and the assembly and integration will be completed by the end of 2015. Advanced Virgo will be part of a network, alongside the two Advanced LIGO detectors in the US and GEO HF in Germany, with the goal of contributing to the early detection of gravitational waves and to opening a new window of observation on the universe. In this paper we describe the main features of the Advanced Virgo detector and outline the status of the construction.
Application of a Hough search for continuous gravitational waves on data from the fifth LIGO science run

J Aasi, J Abadie, B P Abbott, and 875 more authors

Classical and Quantum Gravity, Apr 2014

Abs

We report on an all-sky search for periodic gravitational waves in the frequency range 50¡V1000?Hz with the first derivative of frequency in the range ?8.9 ¡Ѡ10 ?10 Hz?s ?1 to zero in two years of data collected during LIGO¡¦s fifth science run. Our results employ a Hough transform technique, introducing a £q 2 test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95% confidence upper limits on the strain amplitude h 0 . The most stringent upper limit from year 1 is 1.0 ¡Ѡ10 ?24 in the 158.00¡V158.25?Hz band. In year 2, the most stringent upper limit is 8.9 ¡Ѡ10 ?25 in the 146.50¡V146.75?Hz band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein@Home search, will be important for ¡¥quick-look¡¦ searches in the Advanced LIGO and Virgo detector era.
First Searches for Optical Counterparts to Gravitational-wave Candidate Events

J. Aasi, J. Abadie, B. P. Abbott, and 905 more authors

The Astrophysical Journal Supplement Series, Feb 2014

Abs

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.
The NINJA-2 project: detecting and characterizing gravitational waveforms modelled using numerical binary black hole simulations

J Aasi, B P Abbott, R Abbott, and 885 more authors

Classical and Quantum Gravity, May 2014

Abs

The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave (GW) astrophysics communities. The purpose of NINJA is to study the ability to detect GWs emitted from merging binary black holes (BBH) and recover their parameters with next-generation GW observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete BBH hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a ¡¥blind injection challenge¡¦ similar to that conducted in recent Laser Interferometer Gravitational Wave Observatory (LIGO) and Virgo science runs, we added seven hybrid waveforms to two months of data recoloured to predictions of Advanced LIGO (aLIGO) and Advanced Virgo (AdV) sensitivity curves during their first observing runs. The resulting data was analysed by GW detection algorithms and 6 of the waveforms were recovered with false alarm rates smaller than 1 in a thousand years. Parameter-estimation algorithms were run on each of these waveforms to explore the ability to constrain the masses, component angular momenta and sky position of these waveforms. We find that the strong degeneracy between the mass ratio and the BHs¡¦ angular momenta will make it difficult to precisely estimate these parameters with aLIGO and AdV. We also perform a large-scale Monte Carlo study to assess the ability to recover each of the 60 hybrid waveforms with early aLIGO and AdV sensitivity curves. Our results predict that early aLIGO and AdV will have a volume-weighted average sensitive distance of 300 Mpc (1 Gpc) for 10 M ¡󠫠10 M ¡󠨵0 M ¡󠫠50 M ¡󠩠BBH coalescences. We demonstrate that neglecting the component angular momenta in the waveform models used in matched-filtering will result in a reduction in sensitivity for systems with large component angular momenta. This reduction is estimated to be up to ?15% for 50 M ¡󠫠50 M ¡󠂂H coalescences with almost maximal angular momenta aligned with the orbit when using early aLIGO and AdV sensitivity curves.
Gravitational Waves from Known Pulsars: Results from the Initial Detector Era

J. Aasi, J. Abadie, B. P. Abbott, and 894 more authors

The Astrophysical Journal, Apr 2014

Abs

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.
Reconstruction of the gravitational wave signal \textith(t) during the Virgo science runs and independent validation with a photon calibrator

T Accadia, F Acernese, M Agathos, and 192 more authors

Classical and Quantum Gravity, Aug 2014

Abs

The Virgo detector is a kilometer-scale interferometer for gravitational wave detection located near Pisa (Italy). About 13 months of data were accumulated during four science runs (VSR1, VSR2, VSR3 and VSR4) between May 2007 and September 2011, with increasing sensitivity. In this paper, the method used to reconstruct, in the range 10 Hz¡V10 kHz, the gravitational wave strain time series h ( t ) from the detector signals is described. The standard consistency checks of the reconstruction are discussed and used to estimate the systematic uncertainties of the h ( t ) signal as a function of frequency. Finally, an independent setup, the photon calibrator, is described and used to validate the reconstructed h ( t ) signal and the associated uncertainties. The systematic uncertainties of the h ( t ) time series are estimated to be 8% in amplitude. The uncertainty of the phase of h ( t ) is 50 mrad at 10 Hz with a frequency dependence following a delay of ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165013/cqg498626ieqn1.gif] 8;μ\rm s at high frequency. A bias lower than ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165013/cqg498626ieqn2.gif] 4;μ\rm s and depending on the sky direction of the GW is also present.
Implementation of an \mathcalF -statistic all-sky search for continuous gravitational waves in Virgo VSR1 data

J Aasi, B P Abbott, R Abbott, and 846 more authors

Classical and Quantum Gravity, Aug 2014

Abs

We present an implementation of the ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165014/cqg498505ieqn3.gif] \mathcalF -statistic to carry out the first search in data from the Virgo laser interferometric gravitational wave detector for periodic gravitational waves from a priori unknown, isolated rotating neutron stars. We searched a frequency f 0 range from 100 Hz to 1 kHz and the frequency dependent spindown f 1 range from ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165014/cqg498505ieqn4.gif] -1.6(f_0/100;\rm Hz)\times 10^-9 Hz s ?1 to zero. A large part of this frequency¡Vspindown space was unexplored by any of the all-sky searches published so far. Our method consisted of a coherent search over two-day periods using the ?-statistic, followed by a search for coincidences among the candidates from the two-day segments. We have introduced a number of novel techniques and algorithms that allow the use of the fast Fourier transform (FFT) algorithm in the coherent part of the search resulting in a fifty-fold speed-up in computation of the ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165014/cqg498505ieqn6.gif] \mathcalF -statistic with respect to the algorithm used in the other pipelines. No significant gravitational wave signal was found. The sensitivity of the search was estimated by injecting signals into the data. In the most sensitive parts of the detector band more than 90% of signals would have been detected with dimensionless gravitational-wave amplitude greater than ##IMG## [http://ej.iop.org/images/0264-9381/31/16/165014/cqg498505ieqn7.gif] 5\times 10^-24 .
Improved Upper Limits on the Stochastic Gravitational-Wave Background from 2009-2010 LIGO and Virgo Data

J. Aasi, B. P. Abbott, R. Abbott, and 844 more authors

Phys. Rev. Lett., Dec 2014
Multimessenger search for sources of gravitational waves and high-energy neutrinos: Initial results for LIGO-Virgo and IceCube

M. G. Aartsen, M. Ackermann, J. Adams, and 1183 more authors

Phys. Rev. D, Nov 2014
First all-sky search for continuous gravitational waves from unknown sources in binary systems

J. Aasi, B. P. Abbott, R. Abbott, and 847 more authors

Phys. Rev. D, Sep 2014
Search for Gravitational Waves Associated with \ensuremathγ-ray Bursts Detected by the Interplanetary Network

J. Aasi, B. P. Abbott, R. Abbott, and 896 more authors

Phys. Rev. Lett., Jun 2014
Methods and results of a search for gravitational waves associated with gamma-ray bursts using the GEO 600, LIGO, and Virgo detectors

J. Aasi, B. P. Abbott, R. Abbott, and 889 more authors

Phys. Rev. D, Jun 2014
Search for gravitational radiation from intermediate mass black hole binaries in data from the second LIGO-Virgo joint science run

J. Aasi, B. P. Abbott, R. Abbott, and 845 more authors

Phys. Rev. D, Jun 2014
Search for gravitational wave ringdowns from perturbed intermediate mass black holes in LIGO-Virgo data from 2005-2010

J. Aasi, B. P. Abbott, R. Abbott, and 848 more authors

Phys. Rev. D, May 2014
Constraints on Cosmic Strings from the LIGO-Virgo Gravitational-Wave Detectors

J. Aasi, J. Abadie, B. P. Abbott, and 874 more authors

Phys. Rev. Lett., Apr 2014

2013

Search for long-lived gravitational-wave transients coincident with long gamma-ray bursts

J. Aasi, J. Abadie, B. P. Abbott, and 874 more authors

Phys. Rev. D, Dec 2013
Directed search for continuous gravitational waves from the Galactic center

J. Aasi, J. Abadie, B. P. Abbott, and 870 more authors

Phys. Rev. D, Nov 2013

2012

Assessment on the applicability of finite difference methods to model light propagation in photonic liquid crystal fibers

Katarzyna Agnieszka Rutkowska, and Li-Wei Wei

Photonics Letters of Poland, Dec 2012
Full-Vectorial Description of the Light Guidance in Anisotropic Photonic Liquid Crystal Fibers

K. Rutkowska, and L. Wei

Acta Physica Polonica A, Nov 2012