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GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Physical Society 2017 Physical Review Letters Vol.119 No.14
<P>On August 14, 2017 at 10:30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of less than or similar to 1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5(-3.0)(+5.7)M(circle dot) and 25.3(-4.2)(+2.8) M-circle dot (at the 90% credible level). The luminosity distance of the source is 540(-210)(+130) Mpc, corresponding to a redshift of z = 0.11(-0.04)(+0.03). A network of three detectors improves the sky localization of the source, reducing the area of the 90% credible region from 1160 deg(2) using only the two LIGO detectors to 60 deg(2) using all three detectors. For the first time, we can test the nature of gravitational-wave polarizations from the antenna response of the LIGO-Virgo network, thus enabling a new class of phenomenological tests of gravity.</P>
ASTROPHYSICAL IMPLICATIONS OF THE BINARY BLACK HOLE MERGER GW150914
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.818 No.2
<P>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 (greater than or similar to 25M(circle dot)) 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 (greater than or similar to 1 Gpc(-3) yr(-1)) from both types of formation models. The low measured redshift (z similar or equal to 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.</P>
THE RATE OF BINARY BLACK HOLE MERGERS INFERRED FROM ADVANCED LIGO OBSERVATIONS SURROUNDING GW150914
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.833 No.1
<P>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 <4.9 x 10(-6) yr(-1), yielding a p-value for GW150914 of <2 x 10(-7). Parameter estimation follow-up on this trigger identifies its source as a binary black hole (BBH) merger with component masses (m(1), m(2)) = (36(-4)(+5), 29(-4)(+4))M-circle dot at redshift 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 2-53 Gpc(-3) yr(-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 13-600 Gpc(-3) yr(-1) depending on assumptions about the BBH mass distribution. All together, our various rate estimates fall in the conservative range 2-600 Gpc(-3) yr(-1).</P>
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Physical Society 2018 Physical review letters Vol.120 No.9
<P>The LIGO Scientific and Virgo Collaborations have announced the event GW170817, the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star component will add to the contribution from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude Omega(GW) (f = 25 Hz) = 1.8(-1.3)(+2.7) x 10(-9) with 90% confidence, compared with Omega(GW) (f = 25 Hz) = 1.1(-0.7)(+1.2) x 10(-9) from binary black holes alone. Assuming the most probable rate for compact binary mergers, we find that the total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of total observation time, based on the expected timeline for Advanced LIGO and Virgo to reach their design sensitivity.</P>
Observing gravitational-wave transient GW150914 with minimal assumptions
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical Review D Vol.93 No.12
<P>The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches for short-duration gravitational-wave transients. These searches identify time-correlated transients in multiple detectors with minimal assumptions about the signal morphology, allowing them to be sensitive to gravitational waves emitted by a wide range of sources including binary black hole mergers. Over the observational period from September 12 to October 20, 2015, these transient searches were sensitive to binary black hole mergers similar to GW150914 to an average distance of similar to 600 Mpc. In this paper, we describe the analyses that first detected GW150914 as well as the parameter estimation and waveform reconstruction techniques that initially identified GW150914 as the merger of two black holes. We find that the reconstructed waveform is consistent with the signal from a binary black hole merger with a chirp mass of similar to 30 M-circle dot and a total mass before merger of similar to 70 M-circle dot in the detector frame.</P>
Tests of General Relativity with GW150914
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical review letters Vol.116 No.22
<P>The LIGO detection of GW150914 provides an unprecedented opportunity to study the two-body motion of a compact-object binary in the large-velocity, highly nonlinear regime, and to witness the final merger of the binary and the excitation of uniquely relativistic modes of the gravitational field. We carry out several investigations to determine whether GW150914 is consistent with a binary black-hole merger in general relativity. We find that the final remnant's mass and spin, as determined from the low-frequency (inspiral) and high-frequency (postinspiral) phases of the signal, are mutually consistent with the binary black-hole solution in general relativity. Furthermore, the data following the peak of GW150914 are consistent with the least-damped quasinormal mode inferred from the mass and spin of the remnant black hole. By using waveform models that allow for parametrized general-relativity violations during the inspiral and merger phases, we perform quantitative tests on the gravitational-wave phase in the dynamical regime and we determine the first empirical bounds on several high-order post-Newtonian coefficients. We constrain the graviton Compton wavelength, assuming that gravitons are dispersed in vacuum in the same way as particles with mass, obtaining a 90%-confidence lower bound of 1013 km. In conclusion, within our statistical uncertainties, we find no evidence for violations of general relativity in the genuinely strong-field regime of gravity.</P>
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. D.,A American Physical Society 2017 Physical Review D Vol.96 No.2
<P>During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100 M-circle dot, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93 Gpc(-3) yr(-1) in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits.</P>
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.225 No.1
<P>This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands.</P>
GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Physical Society 2017 Physical Review Letters Vol.119 No.16
<P>On August 17, 2017 at 12:41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0 x 10(4) years. We infer the component masses of the binary to be between 0.86 and 2.26 M-circle dot, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60 M-circle dot, with the total mass of the system 2.74(-0.01)(+0.04) M-circle dot. The source was localized within a sky region of 28 deg(2) (90% probability) and had a luminosity distance of 40(-14)(+8) Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the gamma-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short gamma-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.</P>
GW170608: Observation of a 19 Solar-mass Binary Black Hole Coalescence
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.851 No.2
<P>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 12(2)(+7) M-circle dot and 7(2)(+2) M-circle dot (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 340(-140)(+140) Mpc, corresponding to redshift 0.07(-0.03)(+0.03). We verify that the signal waveform is consistent with the predictions of general relativity.</P>