LIGO/Virgo S190814bv is the first high-probability neutron star - black hole (NSBH) merger candidate, whose gravitational waves (GWs) triggered LIGO/Virgo detectors at 21:10:39.012957 UT, 14 August 2019. It has a probability $>99\%$ of being an NSBH merger, with a low false alarm rate (FAR) of 1 per 1.559e+25 years. For an NSBH merger, electromagnetic counterparts (especially short gamma-ray bursts (GRBs)) are generally expected. However, no electromagnetic counterpart has been found in the extensive follow-up observing campaign. In the present work, we propose a novel explanation to this null result. In our scenario, LIGO/Virgo S190814bv is just a GW mirror image of the real NSBH merger which should be detected before 14 September 2015, but at that time we had no ability to detect its GW signals. The electromagnetic counterparts associated with the real NSBH merger should be found in the archive data before 14 September 2015. In this work, we indeed find 9 short GRBs as the possible electromagnetic counterparts.
Gravitational lensing allows the detection of binary black holes (BBH) at cosmological distances with chirp masses that appear to be enhanced by $1+z$ in the range $1<z<4$, in good agreement with the reported BBH masses. We propose this effect also accounts for the puzzling "mass gap" events (MG) newly reported by LIGO/Virgo, as distant, lensed NSBH events with $1<z<4$. The fitted mass of the neutron star member becomes $(1+z)\times 1.4M_\odot$, and is therefore misclassified as a low mass black hole. In this way, we derive a redshift of $z\simeq 3.5$ and $z\simeq 1.0$ for two newly reported "…
The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Interferometer Collaborations have now detected all three classes of compact binary mergers: binary black hole (BBH), binary neutron star (BNS), and neutron star-black hole (NSBH). For coalescences involving neutron stars, the simultaneous observation of gravitational and electromagnetic radiation produced by an event, has broader potential to enhance our understanding of these events, and also to probe the equation of state (EOS) of dense matter. However, electromagnetic follow-up to gravitational wave (GW) events requir…
Short gamma-ray bursts are believed to be produced by both binary neutron star (BNS) and neutron star-black hole (NSBH) mergers. We use current estimates for the BNS and NSBH merger rates to calculate the fraction of observable short gamma-ray bursts produced through each channel. This allows us to constrain merger rates of BNS to $\mathcal{R}_{\rm{BNS}}=384^{+431}_{-213}{\rm{Gpc}^{-3} \rm{yr}^{-1}}$ ($90\%$ credible interval), a $16\%$ decrease in the rate uncertainties from the second LIGO--Virgo Gravitational-Wave Transient Catalog, GWTC-2. Assuming a top-hat emission profile with a large L…
This paper presents a parameter estimation analysis of the seven binary black hole mergers---GW170104, GW170608, GW170729, GW170809, GW170814, GW170818, and GW170823---detected during the second observing run of the Advanced LIGO and Virgo observatories using the gravitational-wave open data. We describe the methodology for parameter estimation of compact binaries using gravitational-wave data, and we present the posterior distributions of the inferred astrophysical parameters. We release our samples of the posterior probability density function with tutorials on using and replicating our resu…
The IceCube neutrino event detected 360 s before the trigger of LIGO/Virgo S190728q is unlikely to be physically associated with the GW event because of an energy budget reason.
Searches for electromagnetic counterparts of gravitational-wave signals have redoubled since the first detection in 2017 of a binary neutron star merger with a gamma-ray burst, optical/infrared kilonova, and panchromatic afterglow. Yet, one LIGO/Virgo observing run later, there has not yet been a second, secure identification of an electromagnetic counterpart. This is not surprising given that the localization uncertainties of events in LIGO and Virgo's third observing run, O3, were much larger than predicted. We explain this by showing that improvements in data analysis that now allow LIGO/Vi…
We anticipate the first direct detections of gravitational waves (GWs) with Advanced LIGO and Virgo later this decade. Though this groundbreaking technical achievement will be its own reward, a still greater prize could be observations of compact binary mergers in both gravitational and electromagnetic channels simultaneously. During Advanced LIGO and Virgo's first two years of operation, 2015 through 2016, we expect the global GW detector array to improve in sensitivity and livetime and expand from two to three detectors. We model the detection rate and the sky localization accuracy for binar…
The third observing run of Advanced LIGO and Advanced Virgo took place between April 2019 and March 2020 and resulted in dozens of gravitational-wave candidates, many of which are now published as confident detections. A crucial requirement of the third observing run has been the rapid identification and public reporting of compact binary mergers, which enabled massive followup observation campaigns with electromagnetic and neutrino observatories. PyCBC Live is a low-latency search for compact binary mergers based on frequency-domain matched filtering, which has been used during the second and…
Data from current gravitational wave detectors contains a high rate of transient noise (glitches) that can trigger false detections and obscure true astrophysical events. Existing noise-detection algorithms largely rely on model-based methods that may miss noise transients unwitnessed by auxiliary sensors or with exotic morphologies. We propose the Unicorn Multi-window Anomaly-detection Pipeline (UniMAP): a model-free algorithm to identify and characterize transient noise leveraging the Temporal Outlier Factor (TOF) via a multi-window data-resampling scheme. We show this windowing scheme exten…
Magnetars are neutron stars with exceptionally strong dipole magnetic fields which are observed to display a range of x-ray flaring behavior, but the flaring mechanism is not well understood. The third observing run of Advanced LIGO and Virgo extended from April 1, 2019 to March 27, 2020, and contained x-ray flares from known magnetar SGR 1935+2154, as well as the newly-discovered magnetar, Swift J1818-1607. We search for gravitational waves coincident with these magnetar flares with minimally modeled, coherent searches which specifically target both short-duration gravitational waves produced…
Gravitational-wave memory, a strong-field effect of general relativity, manifests itself as a permanent displacement in spacetime. We develop a Bayesian framework to detect gravitational-wave memory with the Advanced LIGO/Virgo detector network. We apply this algorithm on the ten binary black hole mergers in LIGO/Virgo's first transient gravitational-wave catalog. We find no evidence of memory, which is consistent with expectations. In order to estimate when memory will be detected, we use the best current population estimates to construct a realistic sample of binary black hole observations f…
In its third observing run, the LIGO/Virgo collaboration has announced a potential neutron star-black hole (NSBH) merger candidate, GW190426_152155. Together with GW190814, these two events belong to a class of binaries with a secondary mass less than $3 \, M_{\odot}$. While the secondary system in GW190426_152155 is consistent with being a neutron star with a mass of $1.5^{+0.8}_{-0.5} \, M_{\odot}$, that of GW190814 is a $2.59^{+0.08}_{-0.09} \, M_{\odot}$ object and counts as the first confirmed detection of a mass-gap object. Here we argue that these two events could have a common origin a…
We show that the inferred merger rate and chirp masses of binary black holes (BBHs) detected by advanced LIGO (aLIGO) can be used to constrain the rate of double neutron star (DNS) and neutron star - black hole (NSBH) mergers in the universe. We explicitly demonstrate this by considering a set of publicly available population synthesis models of \citet{Dominik:2012kk} and show that if all the BBH mergers, GW150914, LVT151012, GW151226, and GW170104, observed by aLIGO arise from isolated binary evolution, the predicted DNS merger rate may be constrained to be $2.3-471.0$~\rate~ and that of NSBH…
Binary neutron star (NS) mergers are among the most promising astrophysical sources of gravitational wave emission for Advanced LIGO and Advanced Virgo, expected to be operational in 2015. Finding electromagnetic counterparts to these signals will be essential to placing them in an astronomical context. The Swift satellite carries a sensitive X-ray telescope (XRT), and can respond to target-of-opportunity requests within 1-2 hours, and so is uniquely poised to find the X-ray counterparts to LIGO/Virgo triggers. Assuming NS mergers are the progenitors of short gamma-ray bursts (GRBs), some perc…
Detecting electromagnetic counterparts to LIGO/Virgo/KAGRA gravitational wave events with DECam: Neutron Star Mergers
Carnegie Mellon University（卡内基梅隆大学）；University of Chicago（芝加哥大学）；University of Ferrara（费拉拉大学）；INFN, Sezione di Ferrara（意大利国家核物理研究所费拉拉分部）；INAF, Osservatorio Astronomico d’Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；Universität Potsdam（波茨坦大学）；Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理学研究所（爱因斯坦研究所））；Utrecht University（乌得勒支大学）；Nikhef（荷兰国家核物理与粒子物理研究所）；California Institute of Technology（加州理工学院）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）
This brief report describes the search for gravitational-wave inspiral signals from short gamma-ray bursts. Since these events are probably created by the merger of two compact objects, a targeted search with a lower threshold can be made. The data around 22 short gamma-ray bursts have been analyzed.
Over the course of the third observing run of LIGO-Virgo-KAGRA Collaboration, several gravitational-wave (GW) neutron star--black hole (NSBH) candidates have been announced. By assuming these candidates are real signals and of astrophysical origins, we analyze the population properties of the mass and spin distributions for GW NSBH mergers. We find that the primary BH mass distribution of NSBH systems, whose shape is consistent with that inferred from the GW binary BH (BBH) primaries, can be well described as a power-law with an index of $α= 4.8^{+4.5}_{-2.8}$ plus a high-mass Gaussian compone…
We compare evolutionary predictions of double compact object merger rate densities with initial and forthcoming LIGO/Virgo upper limits. We find that: (i) Due to the cosmological reach of advanced detectors, current conversion methods of population synthesis predictions into merger rate densities are insufficient. (ii) Our optimistic models are a factor of 18 below the initial LIGO/Virgo upper limits for BH-BH systems, indicating that a modest increase in observational sensitivity (by a factor of 2.5) may bring the first detections or first gravitational wave constraints on binary evolution. (…
By probing the population of binary black hole (BBH) mergers detected by LIGO-Virgo, we can infer properties about the underlying black hole formation channels. A mechanism known as pair-instability (PI) supernova is expected to prevent the formation of black holes from stellar collapse with mass greater than $\sim 40-65\,M_\odot$ and less than $\sim 120\,M_\odot$. Any BBH merger detected by LIGO-Virgo with a component black hole in this gap, known as the PI mass gap, likely originated from an alternative formation channel. Here, we firmly establish GW190521 as an outlier to the stellar-mass B…
New strong non-spiralling-in gravitational wave (GW) source for LIGO/VIRGO detectors are proposed. Double O-Ne-Mg white dwarf mergers can produce strong gravitational waves with frequencies in the several hundreds Hz range. Such events can be followed by a Super Nova type Ia.
Using exclusively the 777 full numerical waveforms of the third Binary Black Holes RIT catalog, we reanalyze the ten black hole merger signals reported in LIGO/Virgo's O1/O2 observation runs. We obtain binary parameters, extrinsic parameters, and the remnant properties of these gravitational waves events which are consistent with, but not identical to previously presented results. We have also analyzed three additional events (GW170121, GW170304, GW170727) reported in Venumadhav et al. 2019, and found closely matching parameters. We finally assess the accuracy of our waveforms with convergence…
We study the impact of the black hole binary population currently probed by LIGO-Virgo on future searches for the primordial gravitational wave background. We estimate the foreground generated by the binaries using the observed event rate and a simple modeling of the black hole population. We subtract individually resolvable binaries from the foreground and utilize Fisher analysis to derive sensitivity curves for power-law signals including these astrophysical foregrounds. Even with optimistic assumptions, we find that the reach of future experiments will be severely reduced.
Mergers of two compact objects, like two neutron stars or a neutron star and a black hole, are the probable progenitor of short gamma-ray bursts. These events are also promising sources of gravitational waves, that are currently motivating related searches by an international network of gravitational wave detectors. Here we describe a search for gravitational waves from the in-spiral phase of two coalescing compact objects, in coincidence with short GRBs occurred during during LIGO's fifth science run and Virgo's first science run. The search includes 22 GRBs for which data from more than one …
Binary black holes are thought to form primarily via two channels: isolated evolution and dynamical formation. The component masses, spins, and eccentricity of a binary black hole system provide clues to its formation history. We focus on eccentricity, which can be a signature of dynamical formation. Employing the spin-aligned eccentric waveform model SEOBNRE, we perform Bayesian inference to measure the eccentricity of binary black hole merger events in the first Gravitational-Wave Transient Catalogue of LIGO and Virgo. We find that all of these events are consistent with zero eccentricity. W…
The NICER Collaboration recently reported the measurement of the mass and radius of a pulsar PSR J0030+0451. We here use this new measurement to constrain one of the higher-order nuclear matter parameters $K_{\mathrm{sym,0}}$. We further combine the tidal measurement of the binary neutron star merger GW170817 by LIGO/Virgo to derive a joint 1-$σ$ constraint as $K_{\mathrm{sym,0}} = -102^{+71}_{-72}$ MeV. We believe this is the most reliable bound on the parameter to date under the assumption that there is no new physics above the saturation density which impacts neutron star observations.
A multi-messenger approach with gravitational-wave transients and high-energy neutrinos is expected to open new perspectives in the study of the most violent astrophysical processes in the Universe. In particular, gamma-ray bursts are of special interest as they are associated with astrophysical scenarios predicting significant joint emission of gravitational waves and high-energy neutrinos. Several experiments (e.g. ANTARES, IceCube, LIGO and Virgo) are currently recording data and searching for those astrophysical sources. In this report, we present the first joint analysis effort using data…
We investigate how to use information on the effective spin parameter of binary black hole mergers from the LIGO-Virgo gravitational wave detections to discriminate the origin of the merging black holes. We calculate the expected probability distribution function for the effective spin parameter for primordial black holes. Using LIGO-Virgo observations, we then calculate odds ratios for different models for the distribution of black holes' spin magnitude and alignment. We evaluate the posterior probability density for a possible mixture of astrophysical and primordial black holes as emerging f…
Search for gravitational waves associated with high-energy neutrinos detected by IceCube during the third observing run of LIGO-Virgo
Universiteit Gent（根特大学）；STAR Institute, Université de Liège（列日大学STAR研究所）；Johns Hopkins University（约翰斯·霍普金斯大学）；University of Catania（卡塔尼亚大学）；Cardiff University（卡迪夫大学）
The detection of gravitational waves (GWs) from binary black holes (BBHs) has allowed the theory of general relativity to be tested in a previously unstudied regime: that of strong curvature and high GW luminosities. One distinctive and measurable effect associated with this aspect of the theory is the nonlinear GW memory effect. The GW memory effect is characterized by its effect on freely falling observers: the proper distance between their locations differs before and after a burst of GWs passes by their locations. Gravitational-wave interferometers, like the LIGO and Virgo detectors, can m…
Constraints on the Population of Common Sources of Gravitational Waves and High-Energy Neutrinos with IceCube During the Third Observing Run of the LIGO and Virgo Detectors
Fermi-Gamma-ray Burst Monitor observed a 1 s long gamma-ray signal (GW150914-GBM) starting 0.4 s after the first gravitational wave detection from the binary black hole merger GW150914. GW150914-GBM is consistent with a short gamma-ray burst origin; however, no unambiguous claims can be made as to the physical association of the two signals due to a combination of low gamma-ray flux and unfavorable location for Fermi-GBM. Here we answer the following question: if GW150914 and GW150914-GBM were associated, how many LIGO-Virgo binary black hole mergers would Fermi-GBM have to follow up to detect…
Our current understanding of the core-collapse supernova explosion mechanism is incomplete, with multiple viable models for how the initial shock wave might be energized enough to lead to a successful explosion. Detection of a gravitational-wave signal emitted in the initial few seconds after stellar core-collapse would provide unique and crucial insight into this process. With the Advanced LIGO and Advanced Virgo detectors expected to approach their design sensitivities soon, we could potentially detect this signal from a supernova within our galaxy. In anticipation of such a scenario, we stu…
Using simulations performed with the population synthesis code MOBSE, we compute the merger rate densities and detection rates of compact binary mergers formed in isolation for second- and third-generation gravitational-wave detectors. We estimate how rates are affected by uncertainties on key stellar-physics parameters, namely common envelope evolution and natal kicks. We estimate how future upgrades will increase the size of the available catalog of merger events, and we discuss features of the merger rate density that will become accessible with third-generation detectors.
The Advanced LIGO and Virgo detectors opened a new era to study black holes (BHs) in our Universe. A population of stellar-mass binary BHs (BBHs) are discovered to be heavier than previously expected. These heavy BBHs provide us an opportunity to achieve multiband observation with ground-based and space-based gravitational-wave (GW) detectors. In this work, we use BBHs discovered by the LIGO/Virgo Collaboration as indubitable examples, and study in great detail the prospects for multiband observation with GW detectors in the near future. We apply the Fisher matrix to spinning, non-precessing i…
Cataclysmic cosmic events can be plausible sources of both gravitational waves (GW) and high-energy neutrinos (HEN). Both GW and HEN are alternative cosmic messengers that may escape very dense media and travel unaffected over cosmological distances, carrying information from the innermost regions of the astrophysical engines. For the same reasons, such messengers could also reveal new, hidden sources that were not observed by conventional photon astronomy. Requiring the consistency between GW and HEN detection channels shall enable new searches as one has significant additional information ab…
We summarize initial results for high-energy neutrino counterpart searches coinciding with gravitational-wave events in LIGO/Virgo's GWTC-2 catalog using IceCube's neutrino triggers. We did not find any statistically significant high-energy neutrino counterpart and derived upper limits on the time-integrated neutrino emission on Earth as well as the isotropic equivalent energy emitted in high-energy neutrinos for each event.
Despite world-wide ground, underground, and space based observations in search of anticipated electromagnetic and perhaps neutrino counterparts to the 29 compact binary merger events, which have been detected by the upgraded LIGO-Virgo gravitational wave detectors in the first half year of their observation period O3, no such counterparts were found. Although such a situation could be due to a poor localization of nearby merger events and/or a complex background of short extragalactic transients, it could be intrinsic. We show that, indeed, it is expected in the cannonball model of gamma ray b…
LIGO's third observing run (O3) has reported several neutron star-black hole (NSBH) merger candidates. From a theoretical point of view, NSBH mergers have received less attention in the community than either binary black holes (BBHs), or binary neutron stars (BNSs). Here we examine single-single (sin-sin) gravitational wave (GW) captures in different types of star clusters -- galactic nuclei (GN), globular clusters (GC), and young stellar clusters (YSC) -- and compare the merger rates from this channel to other proposed merger channels in the literature. There are currently large uncertainties…
Strong lensing of gravitational waves is more likely for distant sources but predicted event rates are highly uncertain with many astrophysical origins proposed. Here we open a new avenue to estimate the event rate of strongly lensed systems by exploring the amplitude of the stochastic gravitational wave background (SGWB). This method can provide a direct upper bound on the high redshift binary coalescing rates, which can be translated into an upper bound on the expected rate of strongly lensed systems. We show that from the ongoing analysis of the Laser Interferometer Gravitational-wave Obser…
The LIGO and Virgo observatories have reported 39 new gravitational-wave detections during the first part of the third observation run, bringing the total to 50. Most of these new detections are consistent with binary black-hole coalescences, making them suitable targets to search for gravitational-wave memory, a non-linear effect of general relativity. We extend a method developed in previous publications to analyse these events to determine a Bayes factor comparing the memory hypothesis to the no-memory hypothesis. Specifically, we calculate Bayes factors using two waveform models with highe…
Searching for gravitational waves from compact binary mergers powering long gamma-ray bursts during LIGO-Virgo-KAGRA's O3 run
Monash University（莫纳什大学）；OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery（引力波发现ARC卓越中心）；Princeton University（普林斯顿大学）；University of Cambridge（剑桥大学）
The first two LIGO and Virgo observation runs have been important milestones in the gravitational wave (GW) field, thanks to the detection of GW signals from ten binary black hole systems and a binary neutron star system. In order to fully characterize the emitting source, the remnant object and its environment, electromagnetic follow-up observations at different wavelengths are essential, as learned from the GW170817/GRB170817A case. Given the quite large localization uncertainties provided by interferometers, the main challenge faced by facilities with a narrow field of view (e.g. Imaging At…
Multi-messenger astronomy is a vast and expanding field as electromagnetic observations (EM) are no longer the only way of exploring the Universe. Due to the new messengers, astrophysical events with both gravitational waves (GWs) and EM emission are no longer a dream of the astronomical community. A breakthrough for GW multi-messenger astronomy came when the LIGO-Virgo network detected a GW signal of two low-mass compact objects consistent with a binary neutron star (BNS, GW170817) an event that generated a short gamma-ray burst (GRBs) and a kilonova. While GW170817 represents the testimony t…
In this letter, we note that the observed in the LIGO / Virgo experiment ratio of the detection rate of black holes to the rate of detection of binary neutron stars requires the assumption of a "conservative" collapse of massive stars into a black hole: almost all the mass of the collapsing star goes under the horizon. This is consistent with the large masses of black holes detected by LIGO/Virgo. On the other hand, the assumption of a small loss of matter during the collapse into a black hole is in good agreement with the small eccentricity of Single-lined Binaries. At the same time, the abse…
The Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo, advanced ground-based gravitational-wave detectors, will begin collecting science data in 2015. With first detections expected to follow, it is important to quantify how well generic gravitational-wave transients can be localized on the sky. This is crucial for correctly identifying electromagnetic counterparts as well as understanding gravitational-wave physics and source populations. We present a study of sky localization capabilities for two search and parameter estimation algorithms: \emph{coherent WaveBurst}, a cons…
The probability number distribution function of binary black hole mergers observed by LIGO/Virgo O3a has double peaks as a function of chirp mass $M_c$, total mass $M_t$, primary black hole mass $M_1$ and secondary one $M_2$, respectively. The larger chirp mass peak is at $M_c \cong 30 M_{\odot}$. The distribution of $M_2$ vs. $M_1$ follows the relation of $M_2\cong 0.7M_1$. For initial mass functions of Population III stars in the form of $f(M) \propto M^{-α}$, population synthesis numerical simulations with $0\leq α\leq 1.5$ are consistent with O3a data for $M_c \gtrsim 20M_{\odot}$. The dis…
Pulsars are spinning neutron stars which emit an electromagnetic beam. We expect pulsars to slowly decrease their rotational frequency. However, sudden increases of the rotational frequency have been observed from different pulsars. These events are called "glitches" and they are followed by a relaxation phase with timescales from days to months. Gravitational wave (GW) emission may follow these peculiar events. We give an overview of the setup for an analysis of GW data from the Advanced LIGO and Virgo third observing run (O3) arXiv:2112.10990 searching for transient GW signals lasting hours …
The LIGO/Virgo collaboration has by now observed or constrained the gravitational merger rates of different classes of compact objects. We consider the possibility that the bulk of these mergers are primordial black hole (PBH) mergers of PBHs formed during the QCD epoch making up the entirety of the dark matter. Having shown in a companion paper that mergers due to the initial binary population formed in the early Universe are likely negligible, we compute current merger rates in PBH clusters in which the typical PBH resides. We consider two scenarios: (i) the PBH mass function dictated by the…
Microlenses with typical stellar masses (a few ${\rm M}_{\odot}$) have traditionally been disregarded as potential sources of gravitational lensing effects at LIGO/Virgo frequencies, since the time delays are often much smaller than the inverse of the frequencies probed by LIGO/Virgo, resulting in negligible interference effects at LIGO/Virgo frequencies. While this is true for isolated microlenses in this mass regime, we show how, under certain circumstances and for realistic scenarios, a population of microlenses (for instance stars and remnants from a galaxy halo or from the intracluster me…
The coalescence of two compact objects is a key target for the new gravitational wave observatories such as Advanced-Virgo (AdV), Advanced-LIGO (aLIGO) and KAGRA. This phenomenon can lead to the simultaneous detection of electromagnetic waves in the form of short GRBs (sGRBs) and gravitational wave transients. This will potentially allow for the first time access to the fireball and the central engine properties. We present an estimation of the detection rate of such events, seen both by a Swift-like satellite and AdV/ALIGO. This rate is derived only from the observations of sGRBs. We show tha…
