We present a thorough observational investigation of the heuristic quantised ringdown model presented in Foit & Kleban (2019). This model is based on the Bekenstein-Mukhanov conjecture, stating that the area of a black hole horizon is an integer multiple of the Planck area $l_P^2$ multiplied by a phenomenological constant, $α$, which can be viewed as an additional black hole intrinsic parameter. Our approach is based on a time-domain analysis of the gravitational wave signals produced by the ringdown phase of binary black hole mergers detected by the LIGO and Virgo collaboration. Employing a full Bayesian formalism and taking into account the complete correlation structure among the black hole parameters, we show that the value of $α$ cannot be constrained using only GW150914, in contrast to what was suggested in Foit & Kleban (2019). We proceed to repeat the same analysis on the new gravitational wave events detected by the LIGO and Virgo Collaboration up to 1 October 2019, obtaining a combined-event measure equal to $α= 15.6^{+20.5}_{-13.3}$ and a combined log odds ratio of $0.1 \pm 0.6$, implying that current data are not informative enough to favour or discard this model against general relativity. We then show that using a population of $\mathcal{O}(20)$ GW150914-like simulated events - detected by the current infrastructure of ground-based detectors at their design sensitivity - it is possible to confidently falsify the quantised model or prove its validity, in which case probing $α$ at the few % level. Finally we classify the stealth biases that may show up in a population study.
Current tests of General Relativity are performed using approximations which neglect a key feature of complete solution of Einstein's theory: higher-order modes. Our analysis will reassess these tests, including these higher-order mode effects. We have chosen to perform inspiral-merger-ringdown consistency tests on the gravitational transients detected by LIGO and Virgo during the observing run O2. We use an approximant which includes all higher modes with $\ell \le 4$ (NRSur7dq2) and then, for the most interesting cases, we repeat the tests involving fits on Numerical Relativity simulations.
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.
According to General Relativity a perturbed black hole will return to a stable configuration by the emission of gravitational radiation in a superposition of quasi-normal modes. Such a perturbation will occur due to the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform, which we refer to as a ringdown, is expected to be dominated by a single mode. As the waveform is well-known the method of matched filtering can be implemented to search for this signal using LIGO data. LIGO is sensitive to the dominant mode of perturbed black holes w…
According to general relativity a perturbed black hole will settle to a stationary configuration by the emission of gravitational radiation. Such a perturbation will occur, for example, in the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform is a superposition of quasi-normal modes, which we refer to as the ringdown. The dominant mode is expected to be the fundamental mode, l=m=2. Since this is a well-known waveform, matched filtering can be implemented to search for this signal using LIGO data. We present a search for gravitational…
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…
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…
A stochastic gravitational wave background is expected to emerge from the superposition of numerous gravitational wave sources of both astrophysical and cosmological origin. A number of cosmological models can have a parity violation, resulting in the generation of circularly polarised gravitational waves. We present a method to search for parity violation in the gravitational wave data. We first apply this method to the most recent, third, LIGO-Virgo observing run. We then investigate the constraining power of future A+ LIGO-Virgo detectors, including KAGRA to the network, for a gravitational…
We summarize the sensitivity achieved by the LIGO and Virgo gravitational wave detectors for low-mass compact binary coalescence (CBC) searches during LIGO's sixth science run and Virgo's second and third science runs. We present strain noise power spectral densities (PSDs) which are representative of the typical performance achieved by the detectors in these science runs. The data presented here and in the accompanying web-accessible data files are intended to be released to the public as a summary of detector performance for low-mass CBC searches during S6 and VSR2-3.
Causality and the generalized laws of black hole thermodynamics imply a bound, known as the \textit{Bekenstein--Hod universal bound}, on the information emission rate of a perturbed system. Using a time-domain ringdown analysis, we investigate whether remnant black holes produced by the coalescences observed by Advanced LIGO and Advanced Virgo obey this bound. We find that the bound is verified by the astrophysical black hole population with $94\%$ probability, providing a first confirmation of the Bekenstein--Hod bound from black hole systems.
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.
We propose a new paradigm in the field of black hole physics, i.e., with more and more high precision observations, one must make a metric selection to determine which black hole is observationally preferred. In light of the shadow imaging data from the Event Horizon Telescope and gravitational wave measurements from the LIGO-VIRGO collaboration, we attempt to address this issue. Although not finding any obvious preference for a specific black hole metric based on current data, as a presentation of this new research paradigm, we rank these black hole metrics using the Bayesian information crit…
We show that the NANOGrav signal can come from the Higgs field with a noncanonical kinetic term in terms of the scalar induced gravitational waves. The scalar induced gravitational waves generated in our model are also detectable by space-based gravitational wave observatories. Primordial black holes with stellar masses that can explain LIGO-Virgo events are also produced. Therefore, the NANOGrav signal and the BHs in LIGO-Virgo events may both originate from the Higgs field.
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. (…
We show that if the new physics beyond the Standard Model is associated with a first-order phase transition around $10^7-10^8$ GeV, the energy density stored in the resulting stochastic gravitational waves and the corresponding peak frequency are within the projected final sensitivity of the advanced LIGO/VIRGO detectors. We discuss some possible new physics scenarios that could arise at such energies, and in particular, the consequences for Peccei-Quinn and supersymmetry breaking scales.
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…
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.
With several dozen binary black hole events detected by LIGO/Virgo to date and many more expected in the next few years, gravitational-wave astronomy is shifting from individual-event analyses to population studies. Using the GWTC-2 catalog, we perform a hierarchical Bayesian analysis that for the first time combines several state-of-the-art astrophysical formation models with a population of primordial black holes (PBHs) and constrains the fraction of a putative subpopulation of PBHs in the data. We find that this fraction depends significantly on the set of assumed astrophysical models. Whil…
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 …
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.
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…
We estimate the expected signal-to-noise ratios (SNRs) from the three phases (inspiral,merger,ringdown) of coalescing binary black holes (BBHs) for initial and advanced ground-based interferometers (LIGO/VIRGO) and for space-based interferometers (LISA). LIGO/VIRGO can do moderate SNR (a few tens), moderate accuracy studies of BBH coalescences in the mass range of a few to about 2000 solar masses; LISA can do high SNR (of order 10^4) high accuracy studies in the mass range of about 10^5 to 10^8 solar masses. BBHs might well be the first sources detected by LIGO/VIRGO: they are visible to much …
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…
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…
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 first generation of ground-based interferometric gravitational wave detectors, LIGO, GEO and Virgo, have operated and taken data at their design sensitivities over the last few years. The data has been examined for the presence of gravitational wave signals. Presented here is a comprehensive review of the most significant results. The network of detectors is currently being upgraded and extended, providing a large likelihood for observations. These future prospects will also be discussed.
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
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…
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…
The no-hair conjecture in General Relativity (GR) states that a Kerr black hole (BH) is completely described by its mass and spin. As a consequence, the complex quasi-normal-mode (QNM) frequencies of a binary-black-hole (BBH) ringdown can be uniquely determined by the mass and spin of the remnant object. Conversely, measurement of the QNM frequencies could be an independent test of the no-hair conjecture. This paper extends to spinning BHs earlier work that proposed to test the no-hair conjecture by measuring the complex QNM frequencies of a BBH ringdown using parameterized inspiral-merger-rin…
Gravitational wave detection from binary black hole (BBH) inspirals has become routine thanks to the LIGO/Virgo interferometers. The nature of these back holes remains uncertain. We study here the spin distributions of LIGO/Virgo black holes from the first catalogue GWTC-1 and the first four published BBH events from run O3. We compute the Bayes evidence for several independent priors: flat, isotropic, spin-aligned and anti-aligned. We find strong evidence for low spins in all of the cases, and significant evidence for small isotropic spins versus any other distribution. When considered as a h…
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 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…
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…
The early inspiral of massive stellar-mass black-hole binaries merging in LIGO's sensitivity band will be detectable at low frequencies by the upcoming space mission LISA. LISA will predict, with years of forewarning, the time and frequency with which binaries will be observed by LIGO. We will, therefore, find ourselves in the position of knowing that a binary is about to merge, with the unprecedented opportunity to optimize ground-based operations to increase their scientific payoff. We apply this idea to detections of multiple ringdown modes, or black-hole spectroscopy. Narrowband tunings ca…
The LIGO Scientific Collaboration and Virgo Collaboration have carried out joint searches in LIGO and Virgo data for periodic continuous gravitational waves. These analyses range from targeted searches for gravitational-wave signals from known pulsars, for which precise ephemerides from radio or X-ray observations are used in matched filters, to all-sky searches for unknown neutron stars, including stars in binary systems. Between these extremes lie directed searches for known stars of unknown spin frequency or for new unknown sources at specific locations, such as near the galactic center or …
We examine the benefits of performing a joint LIGO--Virgo search for transient signals. We do this by adding burst and inspiral signals to 24 hours of simulated detector data. We find significant advantages to performing a joint coincidence analysis, above either a LIGO only or Virgo only search. These include an increased detection efficiency, at a fixed false alarm rate, to both burst and inspiral events and an ability to reconstruct the sky location of a signal.
We report the results of the first search for gravitational waves from compact binary coalescence using data from the LIGO and Virgo detectors. Five months of data were collected during the concurrent S5 (LIGO) and VSR1 (Virgo) science runs. The search focused on signals from binary mergers with a total mass between 2 and 35 Msun. No gravitational waves are identified. The cumulative 90%-confidence upper limits on the rate of compact binary coalescence are calculated for non-spinning binary neutron stars, black hole-neutron star systems, and binary black holes to be 8.7x10^-3, 2.2x10^-3 and 4.…
We examine recent claims that evidence for an overtone in the ringdown of the GW150914 binary black hole merger was a result of noise anomalies. We cannot reproduce these claims, finding that our previous analysis of this event is robust to data analysis choices and consistent with the expectation that strain after the peak is well described as a superposition of quasinormal modes of the remnant black hole. We discuss the meaning and implications of establishing that any specific ringdown mode was detected, and argue that it is misguided to expect actual LIGO-Virgo data to inform the discussio…
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…
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…
We describe the Multi-Band Template Analysis (MBTA) search for gravitational waves signals from coalescences of compact objects in the LIGO-Virgo data, at the time of the third observing run (2019-2020), both for low-latency detections and for offline analysis. Details are given on the architecture and functioning of the pipeline, including transient noise mitigation strategies, parameter space for the searched signals, detection of candidates and evaluation of a false alarm rate associated to them. The performance of the low-latency search is demonstrated based on the LIGO-Virgo third observi…
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…
Scalar fields around black hole binaries in LIGO-Virgo-KAGRA
Université Catholique de Louvain（天主教鲁汶大学）；Royal Observatory of Belgium（比利时皇家天文台）；University of Amsterdam（阿姆斯特丹大学）；Massachusetts Institute of Technology（麻省理工学院）；Queen Mary University of London（伦敦玛丽女王大学）；University of Oxford（牛津大学）
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）
Formation of primordial black holes from inflationary fluctuations is accompanied by a scalar induced gravitational wave background. We perform a Bayesian search of such background in the data from Advanced LIGO and Virgo's first, second and third observing runs, parametrizing the peak in the curvature power spectrum by a log-normal distribution. The search shows no evidence for such a background. We place 95\% confidence level upper limits on the integrated power of the curvature power spectrum peak which, for a narrow width, reaches down to $0.02$ at $10^{17}\,{\rm Mpc}^{-1}$. The resulting …
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…
We place constraints on the normalized energy density in gravitational waves from first-order strong phase transitions using data from Advanced LIGO and Virgo's first, second and third observing runs. First, adopting a broken power law model, we place $95 \%$ confidence level upper limits simultaneously on the gravitational-wave energy density at 25 Hz from unresolved compact binary mergers, $Ω_{\rm CBC} < 6.1 \times 10^{-9}$, and strong first-order phase transitions, $Ω_{\rm BPL} < 4.4 \times 10^{-9}$. The inclusion of the former is necessary since we expect this astrophysical signal to be th…
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 search procedure for burst gravitational waves has been studied using 24 hours of simulated data in a network of three interferometers (Hanford 4-km, Livingston 4-km and Virgo 3-km are the example interferometers). Several methods to detect burst events developed in the LIGO Scientific Collaboration (LSC) and Virgo collaboration have been studied and compared. We have performed coincidence analysis of the triggers obtained in the different interferometers with and without simulated signals added to the data. The benefits of having multiple interferometers of similar sensitivity are demonst…
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…
Sufficient statistics are combinations of data in terms of which the likelihood function can be rewritten without loss of information. Depending on the data volume reduction, the use of sufficient statistics as a preliminary step in a Bayesian analysis can lead to significant increases in efficiency when sampling from posterior distributions of model parameters. Here we show that the frequency integrand of the cross-correlation statistic and its variance are approximate sufficient statistics for ground-based searches for stochastic gravitational-wave backgrounds. The sufficient statistics are …
