DOCSLIB.ORG

Polarization Tests of GW170814 and GW170817 Using Waveforms Consistent with Alternative Theories of Gravity

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Polarization Tests of GW170814 and GW170817 Using Waveforms Consistent with Alternative Theories of Gravity 7th KAGRA International Workshop 2020. 12/19 Polarization tests of GW170814 and GW170817 using waveforms consistent with alternative theories of gravity Hiroki Takeda (University of Tokyo), Atsushi Nishizawa, Soichiro Morisaki Polarization Generic metric theory allows 6 polarizations. A = + , × , x, y, b, l Tensor Plus Cross Vector Vector x Plus mode Vector x mode Breathing mode Vector y Scalar Breathing Cross mode Vector y mode Longitudinal mode Longitudinal 2 Tests of GR by polarization Possible polarization modes in a specific theory. Theory Plus Cross Vector x vector y Breathing Longitudinal General Relativity Kaluza-Klein theory Brans-Dicke theory f(R) theory Bimetric theory Separating the polarization modes from detector signals. ->We can test GR by the polarization modes of the gravitational waves. 3 Detector Signal GW amplitude for polarization mode A Detector signal ̂ A ̂ hI(t, Ω) = ∑ FI (Ω)hA A Antenna pattern functions Plus Cross Vector x represent detector response. Vector y Breathing Longitudinal Detector tensor 4 Reconstruction In principle, (The number of polarizations) = (The number of detectors) % × ( ℎ" = $" ℎ% + $" ℎ× + $" ℎ( % × ( e.g. Detector =3, modes = ( + , × , b) ℎ) = $) ℎ% + $) ℎ× + $) ℎ( % × ( ℎ* = $* ℎ% + $* ℎ× + $* ℎ( Reconstruction(Inverse problem) Detector network expansion → More polarizations can be probed. 5 Motivation Bayesian model selection between GR and the theory allowing only scalar or vector by simple substitution of the antenna pattern functions. [LVC(2017)PRL, LVC(2019)PRL.] Tensor vs Vector T V log BTV > 3 (GW170814) hI = FI hT vs hI = FI hT {log BTV = 20.81 (GW170817) Tensor vs Scalar log B > 2.3 (GW170814) T vs S TS hI = FI hT hI = FI hT {log BTS = 23.09 (GW170817) 1. Lack of consideration of the angular patterns of non-tensorial radiation. -> Re-analysis of pure polarization search in the improved framework. 2. Almost all metric theories of gravity predict the mixed polarization modes. -> Mixed scalar-tensor polarization search. 6 1. Pure polarization search arXiv:2010.14538 Radiation patterns - Re-analyze pure polarization modes considering the angular patterns of radiation. - Inclination angle dependence is determined by the geometry of the system in general. (Orbital angular freq. : , reduced mass: , orbital radius: , retarded time: ) ωs μ r tret 2 2 2 4μωs R sin ι e.g. hb = − cos(2ωstret + 2ϕ) r 2 Normal line Inclinationι Radiation Compact star direction Compact star Revolution plane 8 Analysis : ̂ b ̂ 2 ℋS hI(t, Ω) = FI (Ω)sin ι h+,GR : ̂ x ̂ y ̂ Hypotheses: ℋV hI(t, Ω) = FI (Ω)sin 2ι h+,GR(t) + FI (Ω)sin ι h×,GR(t) 1 + cos2 ι ℋ : h (t, Ω̂ ) = F+(Ω̂ ) h (t) + F×(Ω̂ )cos ι h (t) T I I 2 +,GR I ×,GR h+,GR, h×,GR : Waveforms in GR -> IMRPhenomD, IMRPhenomD_NRTidal parameters: θ = (α, δ, ι, ψ, dL, tc, ϕc, m1, m2, χ1, χ2, Λ1, Λ2) Bayesian inference: prior -> [LVC(2019)PRX.] likelihood p(θ)p(hI |θ, ℋX) posterior p(θ|hI, ℋX) = bilby, p(hI |ℋX) evidence cpnest How much GR is preferred p(hI |ℋX) Bayes factor BXY := compared to pure scalar or p(hI |ℋY) vector model. 9 Result: GW170817(BNS) We impose the priors on - (α, δ, dL) from the host galaxy NGC4993. log BTV = 21.078 log BTS = 44.544 We obtain the improved Bayes factors supporting GR. 10 Result: GW170817(BNS) - In addition, we impose the jet prior on the inclination angle (from the constraint of the observational angle by the gamma ray burst GRB170817A.) 0.25 rad < θobs(dL/41 Mpc) < 0.45 rad [Mooley et. al.(2018)Nature, Hotokezaka et. al.(2019)Nature Astro.] 2.68 rad < ι < 2.92 rad log BTV = 51.043 log BTS = 60.271 The Bayes factors strongly support GR. Metzger and Berger(2012)APJ. 11 2. Scalar-tensor mixed polarization search Analysis - We also search for a mixture of polarization modes: a scalar-tensor polarization model. 1 + cos2 ι ℋ : h (t, Ω̂ ) = F+(Ω̂ ) (1 + δA)h (t)eiδΨ + F×(Ω̂ )cos ι(1 + δA)h (t)eiδΨ ST I I 2 +,GR I ×,GR s=b ̂ 2 iδΨ +FI (Ω)AS sin ιh+,GR(t)e , - Amplitude and phase corrections from the additional scalar radiation . 1 1 Balance law: dE 2, 2 −5/3. = − PGW δA = − AS δΨ = AS (πℳf ) dt Stationary phase approximation3 64 - h+,GR, h×,GR : Waveforms in GR ->TaylorF2, TaylorF2_NRTidal - We perform Bayesian inference for GW170814 (BBH) and for GW170817 (BNS). (Location and jet prior) 13 Result: GW170817(BNS) The estimated amplitude parameters such as the luminosity distance hardly changed. Observational constraint on the amplitude of the additional scalar polarization 14 Summary 1. We obtained Bayes factors that support GR strongly in the pure polarization search. Tensor vs Vector Tensor vs Scalar w/ jet w/ jet prior prior w/o jet prior w/o jet prior BBH BNS BBH BNS 2. We found the constraints on the amplitude ratio between tensor modes and scalar mode. +0.160 +0.0567 BBH RST = − 0.0217 . BNS RST = 0.00378 . −0.154 15 −0.0624 Thank you for your attentions!.
Load more

Recommended publications
  • Stochastic Gravitational Wave Backgrounds
    Stochastic Gravitational Wave Backgrounds Nelson Christensen1;2 z 1ARTEMIS, Universit´eC^oted'Azur, Observatoire C^oted'Azur, CNRS, 06304 Nice, France 2Physics and Astronomy, Carleton College, Northfield, MN 55057, USA Abstract. A stochastic background of gravitational waves can be created by the superposition of a large number of independent sources. The physical processes occurring at the earliest moments of the universe certainly created a stochastic background that exists, at some level, today. This is analogous to the cosmic microwave background, which is an electromagnetic record of the early universe. The recent observations of gravitational waves by the Advanced LIGO and Advanced Virgo detectors imply that there is also a stochastic background that has been created by binary black hole and binary neutron star mergers over the history of the universe. Whether the stochastic background is observed directly, or upper limits placed on it in specific frequency bands, important astrophysical and cosmological statements about it can be made. This review will summarize the current state of research of the stochastic background, from the sources of these gravitational waves, to the current methods used to observe them. Keywords: stochastic gravitational wave background, cosmology, gravitational waves 1. Introduction Gravitational waves are a prediction of Albert Einstein from 1916 [1,2], a consequence of general relativity [3]. Just as an accelerated electric charge will create electromagnetic waves (light), accelerating mass will create gravitational waves. And almost exactly arXiv:1811.08797v1 [gr-qc] 21 Nov 2018 a century after their prediction, gravitational waves were directly observed [4] for the first time by Advanced LIGO [5, 6].
    [Show full text]
  • Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: Gw170817 and Grb 170817A
    GRAVITATIONAL WAVES AND GAMMA-RAYS FROM A BINARY NEUTRON STAR MERGER: GW170817 AND GRB 170817A The gravitational-wave signal GW170817 was detected on August 17, 2017 by the Advanced LIGO and Virgo observatories. This is the first signal thought to be due to the merger of two neutron stars. Only 1.7 seconds after the gravitational-wave signal was detected, the Fermi Gamma-ray Burst Monitor (GBM) and the Anticoincidence Shield for the SPectrometer for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL SPI-ACS) detected a short gamma-ray burst GRB 170817A. For decades astronomers suspected that short gamma-ray bursts were produced by the merger of two neutron stars or a neutron star and a black hole. The combination of GW170817 and GRB 170817A provides the first direct evidence that colliding neutron stars can indeed produce short gamma-ray bursts. INTRODUCTION FIGURES FROM THE PUBLICATION Gamma-Ray Bursts (GRBs) are some of the most energetic events For more information on the meaning of these figures, see the full publication here. observed in Nature. They typically release as much energy in just a few seconds as our Sun will throughout its 10 billion-year life. They occur approximately once a day and come from random points on the sky. These GRBs can last anywhere from fractions of seconds to thousands of seconds. However, we usually divide them in two groups based roughly on their duration, with the division being at the 2 second mark (although more sophisticated features are also taken into account in the classification). Long GRBs (>2 seconds) are caused by the core-collapse of rapidly rotating massive stars.
    [Show full text]
  • R-Process Nucleosynthesis in Neutron Star Mergers and GW170817
    r-Process nucleosynthesis in neutron star mergers and GW170817 Jonas Lippuner July 18, 2018 FRIB and the GW170817 Kilonova FRIB/NSCL/MSU, East Lansing MI Operated by Los Alamos National Security, LLC for the U.S. Department of Energy’s NNSA Los Alamos National Laboratory UNCLASSIFIED LA-UR-18-21867 Outline 1. r-Process nucleosynthesis overview 2. r-Process in neutron star mergers 3. Observational signature and first detection Los Alamos National Laboratory UNCLASSIFIED 3/19/2018 | 2 Solar system abundances Los Alamos National Laboratory UNCLASSIFIED 3/19/2018 | 3 Solar system abundances Los Alamos National Laboratory UNCLASSIFIED 3/19/2018 | 3 The s-process slow neutron capture 90Zr 91Zr 92Zr τ ≪ τ ∼ 2 − 5 89 β− n 10 10 yr Y 84Sr 86Sr 87Sr 88Sr 85Rb 87Rb 78Kr 80Kr 82Kr 83Kr 84Kr 86Kr 79Br 81Br 74Se 76Se 77Se 78Se 80Se 82Se 75As 70Ge 72Ge 73Ge 74Ge 76Ge 69Ga 71Ga 66Zn 67Zn 68Zn 70Zn 65Cu closed neutron shell Los Alamos National Laboratory UNCLASSIFIED 3/19/2018 | 4 The s-process slow neutron capture 90Zr 91Zr 92Zr τ ≪ τ ∼ 2 − 5 89 β− n 10 10 yr Y 84Sr 86Sr 87Sr 88Sr 85Rb 87Rb 78Kr 80Kr 82Kr 83Kr 84Kr 86Kr 79Br 81Br 74Se 76Se 77Se 78Se 80Se 82Se 75As 70Ge 72Ge 73Ge 74Ge 76Ge 69Ga 71Ga 66Zn 67Zn 68Zn 70Zn 65Cu closed neutron shell Los Alamos National Laboratory UNCLASSIFIED 3/19/2018 | 4 The r-process rapid neutron capture 90Zr 91Zr 92Zr τ ≪ τ ∼ n β− 10 ms – 10 s 89Y 84Sr 86Sr 87Sr 88Sr 85Rb 87Rb 78Kr 80Kr 82Kr 83Kr 84Kr 86Kr 79Br 81Br 74Se 76Se 77Se 78Se 80Se 82Se 75As 70Ge 72Ge 73Ge 74Ge 76Ge 69Ga 71Ga 66Zn 67Zn 68Zn 70Zn 65Cu neutron drip
    [Show full text]
  • New Physics and the Black Hole Mass Gap
    New physics and the Black Hole Mass Gap Djuna Lize Croon (TRIUMF) University of Michigan, September 2020 [email protected] | djunacroon.com GW190521 LIGO/Virgo’s biggest discovery yet: the impossible black holes Phys. Rev. Le?. 125, 101102 (2020). From R. Abbo? et al. (LIGO ScienCfic CollaboraCon and Virgo CollaboraCon), GW190521 LIGO/Virgo’s biggest discovery yet: the impossible black holes Phys. Rev. Le?. 125, 101102 (2020). From R. Abbo? et al. (LIGO ScienCfic CollaboraCon and Virgo CollaboraCon), GW190521 LIGO/Virgo’s biggest discovery yet: the impossible black holes … let’s wind back a bit “The Stellar Binary mergers in LIGO/Virgo O1+O2 Graveyard” Adapted from LIGO-Virgo, Frank Elavsky, Aaron Geller “The Stellar Binary mergers in LIGO/Virgo O1+O2 Graveyard” Mass Gap? “Mass Gap” Adapted from LIGO-Virgo, Frank Elavsky, Aaron Geller What populates the stellar graveyard? • In the LIGO/Virgo mass range: remnants of heavy, low-metallicity population-III stars • Primarily made of hydrogen (H) and helium (He) • Would have existed for z ≳ 6, M ∼ 20 − 130 M⊙ • Have not been directly observed yet (JWST target) • Collapsed into black holes in core-collapse supernova explosions. (Or did they?) • We study their evolution from the Zero-Age Helium Branch (ZAHB) <latexit sha1_base64="PYrKTlHPDF1/X3ZrAR6z/bngQPE=">AAACBHicdVDLSgMxFM34rPU16rKbYBFcDTN1StuFUHTjplDBPqAtQyZN29BMMiQZoQxduPFX3LhQxK0f4c6/MX0IKnrgwuGce7n3njBmVGnX/bBWVtfWNzYzW9ntnd29ffvgsKlEIjFpYMGEbIdIEUY5aWiqGWnHkqAoZKQVji9nfuuWSEUFv9GTmPQiNOR0QDHSRgrsXC1IuzKClE/PvYI757Vp0BV9oQM77zquXywWPeg6Z5WS75cNqZS8sleBnuPOkQdL1AP7vdsXOIkI15ghpTqeG+teiqSmmJFptpsoEiM8RkPSMZSjiKheOn9iCk+M0ocDIU1xDefq94kURUpNotB0RkiP1G9vJv7ldRI9KPdSyuNEE44XiwYJg1rAWSKwTyXBmk0MQVhScyvEIyQR1ia3rAnh61P4P2kWHM93Ktd+vnqxjCMDcuAYnAIPlEAVXIE6aAAM7sADeALP1r31aL1Yr4vWFWs5cwR+wHr7BCb+l9Y=</latexit>
    [Show full text]
  • LIGO Listens for Gravitational Waves
    LIGO-Virgo Gravitational-Wave Findings So Far, and Current Events Peter S. Shawhan University of Maryland Physics Department and Joint Space-Science Institute University of Maryland APS Mid-Atlantic Senior Physicists Group February 19, 2020 1 LIGO = Laser Interferometer Gravitational-wave Observatory LIGO Hanford Observatory Two LIGO Observatories LIGO Hanford LIGO Livingston Observatory Plus the Virgo Observatory in Italy Having three detectors significantly improves our ability to confidently detect weak sources and to locate them in the sky 4 Improving detectors over time to reduce the noise level Initial LIGO (2002-2010) Advanced LIGO (as of 2015) 10−23 amplitude spectral density! LIGO-G1501223-v3 5 Advanced Detector Observing Runs O1 — September 12, 2015 to January 19, 2016 LIGO Hanford and Livingston O2 — November 30, 2016 to August 25, 2017 Initially, just the two LIGO observatories Virgo joined on August 1, 2017 O3 — Began April 1, 2019 Both LIGO observatories plus Virgo 6 Ten binary black hole mergers detected in O1+O2! Browse events at https://ligo.northwestern.edu/media/mass-plot/index.html 7 Highlights: Binary Black Hole Mergers Exploring the Properties of GW Events Bayesian parameter estimation: Adjust physical parameters of waveform model to see what fits the data from all detectors well Illustration by N. Cornish and T. Littenberg Get ranges of likely (“credible”) parameter values 9 Population of Merging BBHs: Masses Mass ratio (풒) consistent with 1 for all these events, but with significant uncertainty The data determines “chirp mass” best for low-mass BBHs, and total mass best for high-mass BBHs [Abbott et al.
    [Show full text]
  • Gravitational-Wave Asteroseismology with Fundamental Modes from Compact Binary Inspirals ✉ ✉ ✉ Geraint Pratten 1,2 , Patricia Schmidt 1 & Tanja Hinderer3,4
    ARTICLE https://doi.org/10.1038/s41467-020-15984-5 OPEN Gravitational-wave asteroseismology with fundamental modes from compact binary inspirals ✉ ✉ ✉ Geraint Pratten 1,2 , Patricia Schmidt 1 & Tanja Hinderer3,4 Gravitational waves (GWs) from binary neutron stars encode unique information about ultra- dense matter through characterisic signatures associated with a variety of phenomena including tidal effects during the inspiral. The main tidal signature depends predominantly on Λ 1234567890():,; the equation of state (EoS)-related tidal deformability parameter , but at late times is also characterised by the frequency of the star’s fundamental oscillation mode (f-mode). In General Relativity and for nuclear matter, Λ and the f-modes are related by universal relations which may not hold for alternative theories of gravity or exotic matter. Independently measuring Λ and the f-mode frequency enables tests of gravity and the nature of compact binaries. Here we present directly measured constraints on the f-mode frequencies of the companions of GW170817. We also show that future GW detector networks will measure f- mode frequencies to within tens of Hz, enabling precision GW asteroseismology with binary inspiral signals alone. 1 School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham, Edgbaston, Birmingham B15 9TT, United Kingdom. 2 Universitat de les Illes Balears, Crta. Valldemossa km 7.5, E-07122 Palma, Spain. 3 GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands. 4 Delta Institute for Theoretical ✉ Physics, Science Park 904, 1090 GL Amsterdam, The Netherlands.
    [Show full text]
  • Gravitational Wave Friction in Light of GW170817 and GW190521
    Gravitational wave friction in light of GW170817 and GW190521. C. Karathanasis, Institut de Fisica d'Altes Energies (IFAE) On behalf of S.Mastrogiovanni, L. Haegel, I. Hernadez, D. Steer Published in Journal of Cosmology and Astroparticle Physics, Volume 2021, February 2021, Paper link Iberian Meeting, June 2021 1 Goal of the paper ● We use the gravitational wave (GW) events GW170817 and GW190521, together with their proposed electromagnetic counterparts, to constrain cosmological parameters and theories of gravity beyond General Relativity (GR). ● We consider time-varying Planck mass, large extra-dimensions and a phenomenological parametrization covering several beyond-GR theories. ● In all three cases, this introduces a friction term into the GW propagation equation, effectively modifying the GW luminosity distance. 2 Christos K. - Gravitational wave friction in light of GW170817 and GW190521. Introduction - GW ● GR: gravity is merely an effect caused by the curvature of spacetime. Field equations of GR: Rμ ν−(1/2)gμ ν R=Tμ ν where: • R μ ν the Ricci curvature tensor • g μ ν the metric of spacetime • R the Ricci scalar • T μ ν the energy-momentum tensor ● Einstein solved those and predicted (1916) the existence of disturbances in the curvature of spacetime that propagate as waves, called gravitational waves. ● Most promising sources of GW: Compact Binaries Coalescence (CBC) Binary Black Holes (BBH) Binary Neutron Star (BNS) Neutron Star Black Hole binary (NSBH) ● The metric of spacetime in case of a CBC, and sufficiently far away from it, is: ( B) gμ ν=gμ ν +hμ ν (B) where g μ ν is the metric of the background and h μ ν is the change caused by the GW.
    [Show full text]
  • GW170814 and GW170817 the LIGO/Virgo Detections of Gws from BBH and BNS
    GW170814 and GW170817 the LIGO/Virgo detections of GWs from BBH and BNS José Antonio Font (Universitat de València) www.uv.es/virgogroup Interferometer Detectors Michelson-Morley interferometers. Test masses separated by large distances and suspended as pendulums to isolate them from seismic noise and reduce thermal noise. Analyzing the laser interference fringes allows to control the movement of the masses during their interaction with gravitational radiation. ASTRONOMY: ROEN KELLY The (infinitesimal) change in the length of the arms originates a change in the intensity of the light (interference fringes) at the detector’s output. The Advanced Virgo interferometer The Advanced Virgo interferometer Our current network LIGO Hanford Observatory LIGO Livingston Observatory Virgo Observatory Expanded Network of Interferometers 2020+ Towards a global GW research infrastructure Noise-dominated observations The small amplitude of gravitational waves calls for an extreme reduction of the sources of noise Detectability region Seismic noise Amplitude (h) Amplitude Shot Thermal noise noise Frequency (Hz) If sufficient mergers were detected we could average orbital parameters and use mergers as standard sirens. Numerical relativity simulations needed to extract accurate gravitational waveforms. A “chirp” gravitational waveform signal signal + noise A “chirp” gravitational waveform signal signal + noise A “chirp” gravitational waveform signal signal + noise Advanced technology ultra-vacuum arms (p~10-9 mbar). Movements (vibration) of test mases (40 kg) and suspensions induced by thermal effects. high power lasers (Nd:YAG 1064 nm wavelength laser). Shot noise: fluctuations in the number of photons in the laser produce fluctuations in the signal. highly reflective mirrors (SiO2). monolythic suspension systems to isolate the detectors from vibrations.
    [Show full text]
  • Properties of the Binary Neutron Star Merger GW170817
    Properties of the Binary Neutron Star Merger GW170817 The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Abbott, B.P. et al. “Properties of the Binary Neutron Star Merger GW170817.” Physical Review X 9, 1 (January 2019): 11001 © 2019 The Authors As Published http://dx.doi.org/10.1103/PhysRevX.9.011001 Publisher American Physical Society Version Final published version Citable link https://hdl.handle.net/1721.1/121211 Detailed Terms https://creativecommons.org/licenses/by/4.0/ PHYSICAL REVIEW X 9, 011001 (2019) Properties of the Binary Neutron Star Merger GW170817 B. P. Abbott et al.* (LIGO Scientific Collaboration and Virgo Collaboration) (Received 6 June 2018; revised manuscript received 20 September 2018; published 2 January 2019) On August 17, 2017, the Advanced LIGO and Advanced Virgo gravitational-wave detectors observed a low-mass compact binary inspiral. The initial sky localization of the source of the gravitational-wave signal, GW170817, allowed electromagnetic observatories to identify NGC 4993 as the host galaxy. In this work, we improve initial estimates of the binary’s properties, including component masses, spins, and tidal parameters, using the known source location, improved modeling, and recalibrated Virgo data. We extend the range of gravitational-wave frequencies considered down to 23 Hz, compared to 30 Hz in the initial analysis. We also compare results inferred using several signal models, which are more accurate and incorporate additional physical effects as compared to the initial analysis. We improve the localization of the gravitational-wave source to a 90% credible region of 16 deg2.
    [Show full text]
  • GW170814 : a Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence
    GW170814 : A three-detector observation of gravitational waves from a binary black hole coalescence The LIGO Scientific Collaboration and The Virgo Collaboration 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 ∼ 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 +5:7 +2:8 holes are 30:5 3:0 M and 25:3 4:2 M (at the 90% credible level). The luminosity distance of the source +130 − − +0:03 is 540 210 Mpc, corresponding to a redshift of z =0:11 0:04. A network of three detectors improves the sky localization− of the source, reducing the area of the− 90% credible region from 1160 deg2 using only the two LIGO detectors to 60 deg2 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. PACS numbers: INTRODUCTION in Virgo and a BBH signal only in the LIGO detectors: the three detector BBH signal model is preferred with a Bayes The era of gravitational wave (GW) astronomy began factor of more than 1600. with the detection of binary black hole (BBH) mergers, Until Advanced Virgo became operational, typical GW by the Advanced Laser Interferometer Gravitational Wave position estimates were highly uncertain compared to the Observatory (LIGO) detectors [1], during the first of the fields of view of most telescopes.
    [Show full text]
  • GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run
    PHYSICAL REVIEW X 11, 021053 (2021) GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo during the First Half of the Third Observing Run R. Abbott et al.* (LIGO Scientific Collaboration and Virgo Collaboration) (Received 30 October 2020; revised 23 February 2021; accepted 20 April 2021; published 9 June 2021; corrected 1 September 2021) We report on gravitational-wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 15∶00 UTC and 1 October 2019 15∶00 UTC. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational-wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near-real time through gamma-ray coordinates network notices and circulars; 13 are reported here for the first time. The catalog contains events whose sources are black hole binary mergers up to a redshift of approximately 0.8, as well as events whose components cannot be unambiguously identified as black holes or neutron stars. For the latter group, we are unable to determine the nature based on estimates of the component masses and spins from gravitational-wave data alone. The range of candidate event masses which are unambiguously identified as binary black holes (both objects ≥ 3 M⊙) is increased compared to GWTC-1, with total masses from approximately 14 M⊙ for GW190924_021846 to approximately 150 M⊙ for GW190521.
    [Show full text]
  • GW170817: Implications for the Stochastic Gravitational-Wave
    GW170817: Implications for the Stochastic Gravitational- Wave Background from Compact Binary Coalescences The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Abbott, B.P. et al. “GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences.” Physical Review Letters 120, 9 (February 2018): 091101 © 2018 American Physical Society As Published http://dx.doi.org/10.1103/PHYSREVLETT.120.091101 Publisher American Physical Society (APS) Version Final published version Citable link http://hdl.handle.net/1721.1/117650 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. PHYSICAL REVIEW LETTERS 120, 091101 (2018) Editors' Suggestion GW170817: Implications for the Stochastic Gravitational-Wave Background from Compact Binary Coalescences B. P. Abbott et al.* (LIGO Scientific Collaboration and Virgo Collaboration) (Received 16 October 2017; revised manuscript received 16 January 2018; published 28 February 2018) 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 Ω ðf ¼25 Þ¼1 8þ2.7 10−9 Ω ðf ¼25 Þ¼1 1þ1.2 10−9 GW Hz .
    [Show full text]