Formation of binary black holes (BBHs) detected by gravitational-wave (GW) observations could be broadly divided into two categories: those formed through field binary evolution and those assembled dynamically in dense stellar systems. The branching ratio of the BBHs refers to the contribution of each channel. The dynamical assembly channel would predict a symmetric distribution in the effective spins of the BBHs while field formation predicts BBHs to have positive effective spins. By modeling these two populations based on their effective spin distribution we show that in the 10 BBHs detected by LIGO/Virgo the contribution of the dynamically assembled BBHs to be more than about 50\% with 90\% confidence. This result is based on the assumption that the field binaries are born with positive effective spins not restricted to have small values.
We present a search for gravitational waves from merging binary neutron stars which have non-negligible eccentricity as they enter the LIGO observing band. We use the public Advanced LIGO data which covers the period from 2015 through 2017 and contains $\sim164$ days of LIGO-Hanford and LIGO-Livingston coincident observing time. The search was conducted using matched-filtering using the PyCBC toolkit. We find no significant binary neutron star candidates beyond GW170817, which has previously been reported by searches for binaries in circular orbits. We place a 90% upper limit of $\sim1700$ mer…
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…
Binary neutron stars (BNSs) are the primary source of gravitational waves for the Laser Interferometer Gravitational-Wave Observatory (LIGO) and its international partners Virgo and KAGRA. Current BNS searches target field binaries whose orbits will have circularized by radiation reaction before their gravitational waves enter the Advanced LIGO sensitive band at 15 Hz. It has been suggested that a population of BNSs may form by n-body interactions near supermassive black holes or in globular clusters and that these systems may have non-negligible eccentricity in the Advanced LIGO band. We show…
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…
Binary black holes (BBHs) detected by gravitational wave (GW) observations could be broadly divided into two formation channels: those formed through field binary evolution and those assembled dynamically in dense stellar systems. Each of these formation channels, and their sub-channels, populate a distinct region in the effective spin-mass ($χ_{\rm eff}-M$) plane. Depending on the branching ratio of different channels, an ensemble of BBHs could show a trend in this plane. Here we fit a mass-dependent distribution for $χ_{\rm eff}$ to the GWTC-1 BBHs from the first and second observing runs of…
The predicted rate of binary black hole mergers from galactic fields can vary over several orders of magnitude and is extremely sensitive to the assumptions of stellar evolution. But in dense stellar environments such as globular clusters, binary black holes form by well-understood gravitational interactions. In this letter, we study the formation of black hole binaries in an extensive collection of realistic globular cluster models. By comparing these models to observed Milky Way and extragalactic globular clusters, we find that the mergers of dynamically-formed binaries could be detected at …
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…
Presented is the description of a new and general method used to search for $γ$-ray counterparts to gravitational-wave (GW) triggers. This method is specifically applied to single GW detector triggers. Advanced LIGO data from observing runs O1 and O2 were analyzed, thus each GW trigger comes from either the LIGO-Livingston or the LIGO-Hanford interferometer. For each GW trigger, Fermi Gamma-ray Burst Monitor data is searched and the most significant subthreshold signal counterpart is selected. Then, a methodology is defined in order to establish which of GW-$γ$-ray pairs are likely to have a c…
We present the first Open Gravitational-wave Catalog (1-OGC), obtained by using the public data from Advanced LIGO's first observing run to search for compact-object binary mergers. Our analysis is based on new methods that improve the separation between signals and noise in matched-filter searches for gravitational waves from the merger of compact objects. The three most significant signals in our catalog correspond to the binary black hole mergers GW150914, GW151226, and LVT151012. We assume a common population of binary black holes for these three signals by defining a region of parameter s…
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. (…
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）
In this paper, we report on the construction of a new and independent pipeline for analyzing the public data from the first observing run of advanced LIGO for mergers of compact binary systems. The pipeline incorporates different techniques and makes independent implementation choices in all its stages including the search design, the method to construct template banks, the automatic routines to detect bad data segments ("glitches") and to insulate good data from them, the procedure to account for the non-stationary nature of the detector noise, the signal-quality vetoes at the single-detector…
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…
The nature of gravitational waves in a generalized gravitation theory is investigated. The linearized field equations and the metric tensor quadrupole moment power and the decrease in radius of an inspiralling binary system of two compact objects are derived. The generalized Kerr metric describing a spinning black hole is determined by its mass $M$ and the spin parameter $a=cS/GM^2$. The LIGO-Virgo collaboration data is fitted with smaller binary black hole masses in agreement with the current electromagnetic, observed X-ray binary upper bound for a black hole mass, $M\lesssim 10M_\odot$.
We adopt the Pearson cross-correlation measure to analyze the LIGO Hanford and LIGO Livingston detector data streams around the events GW150914, GW151012,GW151226 and GW170104. We find that the Pearson cross-correlation method is sensitive to these signals, with correlations peaking when the black hole binaries reconstructed by the LIGO Scientific and Virgo Collaborations, are merging. We compare the obtained cross-correlations with the statistical correlation fluctuations arising in simulated Gaussian noise data and in LIGO data at times when no event is claimed. Our results for the significa…
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 present the second Open Gravitational-wave Catalog (2-OGC) of compact-binary coalescences, obtained from the complete set of public data from Advanced LIGO's first and second observing runs. For the first time we also search public data from the Virgo observatory. The sensitivity of our search benefits from updated methods of ranking candidate events including the effects of non-stationary detector noise and varying network sensitivity; in a separate targeted binary black hole merger search we also impose a prior distribution of binary component masses. We identify a population of 14 binary…
We compare binary evolution models with different assumptions about black-hole natal kicks to the first gravitational-wave observations performed by the LIGO detectors. Our comparisons attempt to reconcile merger rate, masses, spins, and spin-orbit misalignments of all current observations with state-of-the-art formation scenarios of binary black holes formed in isolation. We estimate that black holes (BHs) should receive natal kicks at birth of the order of $σ\simeq 200$ (50) km/s if tidal processes do (not) realign stellar spins. Our estimate is driven by two simple factors. The natal kick d…
The binary black hole mergers observed by LIGO-Virgo gravitational-wave detectors pose two major challenges: (i) how to produce these massive black holes from stellar processes; and (ii) how to bring them close enough to merge within the age of the universe? We derive a fundamental constraint relating the binary separation and the available stellar budget in the universe to produce the observed black hole mergers. We find that $\lesssim 14\%$ of the entire budget contributes to the observed merger rate of $(30 + 30)~\mathrm{M}_\odot$ black holes, if the separation is around the diameter of the…
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…
It may soon be possible for Advanced LIGO to detect hundreds of binary black hole mergers per year. We show how the accumulation of many such measurements will allow for the detection of gravitational-wave memory: a permanent displacement of spacetime that comes from strong-field, general relativistic effects. We estimate that Advanced LIGO operating at design sensitivity may be able to make a signal-to-noise ratio 3(5) detection of memory with ~35 (90) events with masses and distance similar to GW150914. We highlight the importance of incorporating higher-order gravitational-wave modes for pa…
2015 will see the first observations of Advanced LIGO and the start of the gravitational-wave (GW) advanced-detector era. One of the most promising sources for ground-based GW detectors are binary neutron-star (BNS) coalescences. In order to use any detections for astrophysics, we must understand the capabilities of our parameter-estimation analysis. By simulating the GWs from an astrophysically motivated population of BNSs, we examine the accuracy of parameter inferences in the early advanced-detector era. We find that sky location, which is important for electromagnetic follow-up, can be det…
We study the gravitational wave (GW) frequency and chirp mass distribution of binary black hole (BBH) mergers assembled through three-body interactions in globular clusters (GCs), when GW emission at the 2.5 post-Newtonian (PN) level is included in the $N$-body equation-of-motion (EOM). From performing $\sim 2.5\times10^{6}$ PN binary-single interactions based on GC data from the `MOCCA-Survey Database I' project, and by the use of analytical methods, we find that $5-10\%$ of all the three-body assembled GC BBH mergers have a GW frequency at formation that is $\gtrsim 10^{-1}$ Hz, implying the…
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…
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…
Gravitational waves from binary black holes have the potential to yield information on both of the intrinsic parameters that characterize the compact objects: their masses and spins. While the component masses are usually resolvable, the component spins have proven difficult to measure. This limitation stems in great part from our choice to inquire about the spins of the most and least massive objects in each binary, a question that becomes ill-defined when the masses are equal. In this paper we show that one can ask a different question of the data: what are the spins of the objects with the …
External Attention Transformer: A Robust AI Model for Identifying Initial Eccentricity Signatures in Binary Black Hole Events in Simulated Advanced LIGO Data
Possible formation mechanisms of massive close binary black holes that can merge in the Hubble time to produce powerful gravitational wave bursts detected during advanced LIGO O1 science run are briefly discussed. The pathways include the evolution from field low-metallicity massive binaries, the dynamical formation in globular clusters and primordial black holes. Low effective black hole spins inferred for LIGO GW150914 and LTV151012 events are discussed. Population synthesis calculations of the expected spin and chirp mass distributions from the standard field massive binary formation channe…
A Search for Binary Black Hole Mergers in LIGO O1-O3 Data with Convolutional Neural Networks
Harvard University（哈佛大学）；The NSF AI Institute for Artificial Intelligence and Fundamental Interactions（美国国家科学基金会人工智能基础相互作用研究所）；Faculty of Arts and Sciences Research Computing, Harvard University（哈佛大学本科研究院计算研究部）；Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森天体物理中心）
The joint detection of GW170817 and GRB 170817A opened the era of multi-messenger astronomy with gravitational waves (GWs) and provided the first direct probe that at least some binary neutron star (BNS) mergers are progenitors of short gamma-ray bursts (S-GRBs). In the next years, we expect to have more multi-messenger detections of BNS mergers, thanks to the increasing sensitivity of GW detectors. Here, we present a comprehensive study on the prospects for joint GW and electromagnetic observations of merging BNSs in the fourth LIGO--Virgo--KAGRA observing run with \emph{Fermi}, \emph{Swift},…
The LIGO/Virgo gravitational--wave observatories have detected 50 BH-BH coalescences. This sample is large enough to have allowed several recent studies to draw conclusions about the branching ratios between isolated binaries versus dense stellar clusters as the origin of double BHs. It has also led to the exciting suggestion that the population is highly likely to contain primordial black holes. Here we demonstrate that such conclusions cannot yet be robust, because of the large current uncertainties in several key aspects of binary stellar evolution. These include the development and surviva…
In LIGO's O1 and O2 observational runs, the detectors were sensitive to stellar mass binary black hole coalescences with component masses up to $100\,M_\odot$, with binaries with primary masses above $40\,M_\odot$ representing $\gtrsim90\%$ of the total accessible sensitive volume. Nonetheless, of the 5.9 detections (GW150914, LVT151012, GW151226, GW170104, GW170608, GW170814) reported by LIGO-Virgo, the most massive binary detected was GW150914 with a primary component mass of $\sim36\,M_\odot$, far below the detection mass limit. Furthermore, there are theoretical arguments in favor of an up…
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…
The primary and secondary masses of the binary black holes (BBH) reported by LIGO/Virgo are correlated with a narrow dispersion that appears to increase in proportion to mass. The mean binary mass ratio $1.45\pm0.07$ we show is consistent with pairs drawn randomly from the mass distribution of black holes in our Galaxy. However, BBH masses are concentrated around $\simeq 30M_\odot$, whereas black holes in our Galaxy peak at $\simeq 10M_\odot$. This mass difference can be reconciled by gravitational lensing magnification which allows distant events to be detected with typically $z\simeq 2$, so …
Intermediate-mass black holes (IMBHs) span the approximate mass range $100$--$10^5\,M_\odot$, between black holes (BHs) formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mas…
We report a new binary black hole merger in the publicly available LIGO First Observing Run (O1) data release. The event has an inverse false alarm rate of one per six years in the detector-frame chirp-mass range $\mathcal{M}^{\rm det} \in [20,40]M_\odot$ in a new independent analysis pipeline that we developed. Our best estimate of the probability that the event is of astrophysical origin is $P_{\rm astro} \sim 0.71\, .$ The estimated physical parameters of the event indicate that it is the merger of two massive black holes, $\mathcal{M}^{\rm det} = 31^{+2}_{-3}\,M_\odot$ with an effective sp…
We present a critical reanalysis of the black-hole binary coalescences detected during LIGO's first observing run under different Bayesian prior assumptions. We summarize the main findings of Vitale et al. (2017) and show additional marginalized posterior distributions for some of the binaries' intrinsic parameters.
The distribution of effective spin $χ_{\rm eff}$, a parameter that encodes the degree of spin-orbit alignment in a binary system, has been widely regarded as a robust discriminator between the isolated and dynamical formation pathways for merging binary black holes. Until the recent release of the GWTC-2 catalog, such tests have yielded inconclusive results due to the small number of events with measurable nonzero spins. In this work, we study the $χ_{\rm eff}$ distribution of the binary black holes detected in the LIGO-Virgo O1-O3a observing runs. Our focus is on the degree to which the $χ_{\…
Here we investigate within the context of field binary progenitors how the the spin of LIGO sources vary when the helium star-descendent black hole (BH) is formed in a failed supernova (SN) explosion rather than by direct collapse. To this end, we make use of 3d hydrodynamical simulations of fallback supernova in close binary systems with properties designed to emulate LIGO sources. By systematically varying the explosion energy and the binary properties, we are able to explore the effects that the companion has on redistributing the angular momentum of the system. We find that, unlike the mas…
In August 2017, the first detection of a binary neutron star merger, GW170817, made it possible to study neutron stars in compact binary systems using gravitational waves. Despite being the loudest gravitational wave event detected to date (in terms of signal-to-noise ratio), it was not possible to unequivocally determine that GW170817 was caused by the merger of two neutron stars instead of two black holes from the gravitational-wave data alone. That distinction was primarily due to the accompanying electromagnetic counterpart. This raises the question: under what circumstances can gravitatio…
The frequent detection of binary mergers of $\sim 30 M_{\odot}$ black holes (BHs) by the Laser Interferometer Gravitational-Wave Observatory (LIGO) rekindled researchers' interest in primordial BHs (PBHs) being dark matter (DM). In this work, we looked at PBHs distributed as DM with a monochromatic mass of $30 M_{\odot}$ and examined the encounter-capture scenario of binary formation, where the densest central region of DM halo dominates. Thus, we paid special attention to the tidal effect by the supermassive black hole (SMBH) present. In doing so, we discovered a necessary tool called loss zo…
We derive the first constraints on the time delay distribution of binary black hole (BBH) mergers using the LIGO-Virgo Gravitational-Wave Transient Catalog GWTC-2. Assuming that the progenitor formation rate follows the star formation rate (SFR), the data favor that $43$--$100\%$ of mergers have delay times $<4.5$ Gyr (90% credibility). Adopting a model for the metallicity evolution, we derive joint constraints for the metallicity-dependence of the BBH formation efficiency and the distribution of time delays between formation and merger. Short time delays are favored regardless of the assumed …
GW170817 showed that neutron star mergers not only emit gravitational waves but also can release electromagnetic signatures in multiple wavelengths. Within the first half of the third observing run of the Advanced LIGO and Virgo detectors, there have been a number of gravitational wave candidates of compact binary systems for which at least one component is potentially a neutron star. In this article, we look at the candidates S190425z, S190426c, S190510g, S190901ap, and S190910h, predicted to have potentially a non-zero remnant mass, in more detail. All these triggers have been followed up wi…
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…
We can be biased against observing massive black holes to merge in the local universe as the bounds on the maximum black hole mass ($M_{BH}^{\rm max}$) depends on the assumptions regarding the metallicity evolution of the star forming gas across the cosmic time. We investigate the bounds on the metallicity evolution, mass distribution and delay times of the binary black hole sources based on the ten observed events by LIGO. We parametrize $M_{BH}^{\rm max}$ to be a function of metallicity which itself is modeled to evolve with redshift in either a modest or rapid fashion. Rapid metallicity evo…
LIGO's detection of gravitational waves from binary black hole mergers was an unexpected surprise that immediately raised the question - what is the origin of these black hole binaries? The "simplest" scenario is evolution of field massive stellar binaries. However, other possibilities involving capture have been proposed. We explore here one of the more interesting clues on this puzzle: the relatively modest spins of the resulting black holes that imply that the progenitor black holes were not spinning rapidly. More specifically we consider the implication of observed distribution of, $χ_{\rm…
Within the next five years, it is expected that the Advanced LIGO/Virgo network will have reached a sensitivity sufficient to enable the routine detection of gravitational waves. Beyond the initial detection, the scientific promise of these instruments relies on the effectiveness of our physical parameter estimation capabilities. The majority of this effort has been towards the detection and characterization of gravitational waves from compact binary coalescence, e.g. the coalescence of binary neutron stars. While several previous studies have investigated the accuracy of parameter estimation …
All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported from the O1/O2 runs have near zero effective spins. There are only three potential explanations of this fact. If the BH spin magnitudes are large then (i) either both BH spin vectors must be nearly in the orbital plane or (ii) the spin angular momenta of the BHs must be oppositely directed and similar in magnitude. Or, (iii) the BH spin magnitudes are small. We test the third hypothesis within the framework of the classical isolated binary evolution scenario of the BH-BH merger formation. We test three models of angular momentu…
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…
We explore the implications of the observed low spins aligned with the orbital axis in Advanced~LIGO~O1 run on binary black hole (BBH)~merger scenarios in which the merging BBHs have evolved from field binaries. The coalescence time determines the initial orbital separation of BBHs. This, in turn, determines whether the stars are synchronized before collapse and hence determines their projected spins. Short coalescence times imply synchronization and large spins. Among known stellar objects, Wolf-Rayet~(WR) stars seem the only progenitors consistent with the low aligned spins observed in LIGO'…
With the black hole mass function (BHMF; assuming an exponential cutoff at a mass of $\sim 40\,M_\odot$) of coalescing binary black hole systems constructed with the events detected in the O1 run of the advanced LIGO/Virgo network, Liang et al.(2017) predicted that the birth of the lightest intermediate mass black holes (LIMBHs; with a final mass of $\gtrsim 100\,M_\odot$) is very likely to be caught by the advanced LIGO/Virgo detectors in their O3 run. The O1 and O2 observation run data, however, strongly favor a cutoff of the BHMF much sharper than the exponential one. In this work we show t…
The growing sample of LIGO--Virgo black holes (BHs) opens new perspectives for the study of massive binary evolution. Here, we study the impact of mass accretion efficiency and common envelope on the properties of binary BH (BBH) mergers, by means of population synthesis simulations. We model mass accretion efficiency with the parameter $f_{\rm MT}\in[0.05,1]$, which represents the fraction of mass lost from the donor which is effectively accreted by the companion. Lower values of $f_{\rm MT}$ result in lower BBH merger rate densities and produce mass spectra skewed towards lower BH masses. Ou…
The growing population of compact binary mergers detected with gravitational waves contains multiple events that are challenging to explain through isolated binary evolution. Such events have higher masses than are expected in isolated binaries, component spin-tilt angles that are misaligned, and/or non-negligible orbital eccentricities. We investigate the orbital eccentricities of 62 binary black hole candidates from the third gravitational-wave transient catalogue of the LIGO-Virgo-KAGRA Collaboration with an aligned-spin, moderate-eccentricity waveform model. Within this framework, we find …
