scholarly journals Merger rate density of binary black holes formed in open clusters

2020 ◽  
Vol 495 (4) ◽  
pp. 4268-4278 ◽  
Author(s):  
Jun Kumamoto ◽  
Michiko S Fujii ◽  
Ataru Tanikawa
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Open Clusters ◽  
Star Formation History ◽  
Formation Mechanisms ◽  
Binary Black Holes ◽  
Formation History ◽  
Solar Metallicity ◽  
Binary Evolution ◽  
Merger Rate

ABSTRACT Several binary black holes (BBHs) have been observed using gravitational wave detectors. For the formation mechanism of BBHs, two main mechanisms, isolated binary evolution and dynamical formation in dense star clusters, have been suggested. Future observations are expected to provide more information about BBH distributions, and it will help us to distinguish the two formation mechanisms. For the star cluster channel, globular clusters have mainly been investigated. However, recent simulations have suggested that BBH formation in open clusters is not negligible. We estimate a local merger rate density of BBHs originated from open clusters using the results of our N-body simulations of open clusters with four different metallicities. We find that the merger rate per cluster is the highest for our 0.1 solar metallicity model. Assuming a cosmic star formation history and a metallicity evolution with dispersion, we estimate the local merger rate density of BBHs originated from open clusters to be ∼70 yr−1 Gpc−3. This value is comparable to the merger rate density expected from the first and second observation runs of LIGO and Virgo. In addition, we find that BBH mergers obtained from our simulations can reproduce the distribution of primary mass and mass ratio of merging BBHs estimated from the LIGO and Virgo observations.

scholarly journals Hidden infrared star clusters in our Galaxy: follow-up observations

2009 ◽  
Vol 5 (S266) ◽  
pp. 366-366
Author(s):  
Jura Borissova ◽  
Radostin Kurtev ◽  
Margaret M. Hanson ◽  
Leonid Georgiev ◽  
Valentin Ivanov ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Star Cluster ◽  
Open Clusters ◽  
Star Formation History ◽  
Stellar Disk ◽  
Physical Parameters ◽  
Formation History ◽  
The Galaxy ◽  
History Of ◽  
Infrared Star

AbstractWe are reporting some recent results from our long-term program aimed at characterizing the obscured present-day star cluster population in the Galaxy. Our goal is to expand the current census of the Milky Way's inner stellar disk to guide models seeking to understand the structure and recent star-formation history of our Galaxy. The immediate goal is to derive accurate cluster physical parameters using precise infrared photometry and spectroscopy. So far, we observed approximately 60 star cluster candidates selected from different infrared catalogs. Their nature, reddening, distance, age and mass are analyzed. Two of them, Mercer 3 and Mercer 5, are new obscured Milky Way globular clusters. Among the newly identified open clusters, the objects [DBS2003] 179, Mercer 23, Mercer 30, Mercer 70, and [DBS2003] 106 are particularly interesting because they contain massive young OB and Wolf–Rayet stars with strong emission lines.

scholarly journals Progenitors of binary black hole mergers detected by LIGO

2016 ◽  
Vol 12 (S329) ◽  
pp. 118-125 ◽  
Author(s):  
Konstantin Postnov ◽  
Alexander Kuranov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Close Binary ◽  
Formation Mechanisms ◽  
Binary Black Holes ◽  
Mass Distributions ◽  
Metal Abundance ◽  
Population Iii Stars

AbstractPossible 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 channel are presented for different metallicities (from zero-metal Population III stars up to solar metal abundance). We conclude that that merging binary black holes can contain systems from different formation channels, discrimination between which can be made with increasing statistics of mass and spin measurements from ongoing and future gravitational wave observations.

Unexpectedly high formation rate of merging binary black holes in open clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 204-207
Author(s):  
Jun Kumamoto ◽  
Michiko S. Fujii ◽  
Ataru Tanikawa
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Formation Rate ◽  
Mass Function ◽  
Open Clusters ◽  
Binary Black Holes ◽  
Initial Cluster ◽  
Three Body ◽  
The Universe ◽  
Hubble Time

AbstractGravitational wave direct detections suggest that 30 M⊙ binary black holes (BBHs) commonly exist in the universe. One possible formation scenario of such BBHs is dynamical three-body encounters in dense star clusters. We performed a series of direct N-body simulations with a mass of 2500 and 10000 M⊙ and found a new channel for the formation of BBHs which is dominant in open clusters. In open clusters, the core-collapse time is shorter than in globular clusters, and therefore massive main-sequence (MS) binaries can form before they evolve to BHs. These MS binaries experience common envelope evolution and evolve to hard BBHs, which can merge within the Hubble time. The number of BBH mergers per unit mass obtained from our simulations reached 20–50 % of that for globular clusters, assuming an initial cluster mass function. Thus, open clusters can be a dominant formation site of hard BBHs.

scholarly journals Binary black holes in young star clusters: the impact of metallicity

2020 ◽  
Vol 498 (1) ◽  
pp. 495-506 ◽  
Author(s):  
Ugo N Di Carlo ◽  
Michela Mapelli ◽  
Nicola Giacobbo ◽  
Mario Spera ◽  
Yann Bouffanais ◽  
...  
Keyword(s):  
Black Holes ◽  
Initial Density ◽  
Star Clusters ◽  
Young Star ◽  
Binary Black Holes ◽  
Binary Evolution ◽  
Merger Rate ◽  
The Masses ◽  
The Impact ◽  
Young Star Clusters

ABSTRACT Young star clusters are the most common birthplace of massive stars and are dynamically active environments. Here, we study the formation of black holes (BHs) and binary black holes (BBHs) in young star clusters, by means of 6000 N-body simulations coupled with binary population synthesis. We probe three different stellar metallicities (Z = 0.02, 0.002, and 0.0002) and two initial-density regimes (density at the half-mass radius ρh ≥ 3.4 × 104 and ≥1.5 × 102 M⊙ pc−3 in dense and loose star clusters, respectively). Metal-poor clusters tend to form more massive BHs than metal-rich ones. We find ∼6, ∼2, and <1 per cent of BHs with mass mBH > 60 M⊙ at Z = 0.0002, 0.002, and 0.02, respectively. In metal-poor clusters, we form intermediate-mass BHs with mass up to ∼320 M⊙. BBH mergers born via dynamical exchanges (exchanged BBHs) can be more massive than BBH mergers formed from binary evolution: the former (latter) reach total mass up to ∼140 M⊙ (∼80 M⊙). The most massive BBH merger in our simulations has primary mass ∼88 M⊙, inside the pair-instability mass gap, and a mass ratio of ∼0.5. Only BBHs born in young star clusters from metal-poor progenitors can match the masses of GW 170729, the most massive event in first and second observing run (O1 and O2), and those of GW 190412, the first unequal-mass merger. We estimate a local BBH merger rate density ∼110 and ∼55 Gpc−3 yr−1, if we assume that all stars form in loose and dense star clusters, respectively.

scholarly journals Searching for eccentricity: signatures of dynamical formation in the first gravitational-wave transient catalogue of LIGO and Virgo

2019 ◽  
Vol 490 (4) ◽  
pp. 5210-5216 ◽  
Author(s):  
Isobel M Romero-Shaw ◽  
Paul D Lasky ◽  
Eric Thrane
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Bayesian Inference ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Reference Frequency ◽  
Binary Black Holes ◽  
Binary Black Hole ◽  
Upper Limits ◽  
Formation History

ABSTRACT 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. We set upper limits on eccentricity ranging from 0.02 to 0.05 with 90  per cent confidence at a reference frequency of $10\, {\rm Hz}$. These upper limits do not significantly constrain the fraction of LIGO–Virgo events formed dynamically in globular clusters, because only $\sim 5{{\ \rm per\ cent}}$ are expected to merge with measurable eccentricity. However, with the gravitational-wave transient catalogue set to expand dramatically over the coming months, it may soon be possible to significantly constrain the fraction of mergers taking place in globular clusters using eccentricity measurements.

scholarly journals Chirp mass and spin of binary black holes from first star remnants

2020 ◽  
Vol 498 (3) ◽  
pp. 3946-3963 ◽  
Author(s):  
Tomoya Kinugawa ◽  
Takashi Nakamura ◽  
Hiroyuki Nakano
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
High Redshift ◽  
Spin Distribution ◽  
Binary Black Holes ◽  
Effective Spin ◽  
Einstein Telescope ◽  
Evolution Study ◽  
Binary Evolution ◽  
Merger Rate

ABSTRACT We performed Population III (Pop III) binary evolution using population synthesis simulations for seven different models. We found that Pop III binaries tend to be binary black holes (BBHs) with chirp mass Mchirp ∼ 30 M⊙ and they can merge in the present day, due to a long merger time. The merger rate densities of Pop III BBHs at z = 0 are in the range 3.34–21.2 $\rm yr^{-1}\,Gpc^{-3}$ which is consistent with the Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO)/Advanced Virgo (aVIRGO) result of 9.7–101 $\rm yr^{-1}\,Gpc^{-3}$. These Pop III binaries might contribute some portion of the massive BBH gravitational wave (GW) sources detected by aLIGO/aVIRGO. We also calculated the redshift dependence of Pop III BBH mergers. We found that Pop III low-spin BBHs tend to merge at low redshift, while Pop III high-spin BBHs merge at high redshift, which can be confirmed by future GW detectors such as Einstein Telescope (ET), Cosmic Explorer (CE), and DECi-hertz Interferometer Gravitational wave Observatory (DECIGO). These detectors can also check the redshift dependence of the BBH merger rate and spin distribution. Our results show that, except for one model, the mean effective spin 〈χeff〉 at z = 0 lies in the range 0.02–0.3, while at z = 10 it is 0.16–0.64. Therefore, massive stellar-mass BBH detection by GWs will be key for stellar evolution study in the early Universe.

scholarly journals On Dark Gravitational Wave Standard Sirens as Cosmological Inference and Forecasting the Constraint on Hubble Constant using Binary Black Holes Detected by Deci-Hertz Observator

2021 ◽  
Author(s):  
Ju Chen ◽  
Changshuo Yan ◽  
Youjun Lu ◽  
Yuetong Zhao ◽  
Junqiang Ge
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Signal To Noise Ratio ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Luminosity Distance ◽  
Host Galaxies ◽  
Binary Black Holes ◽  
Merger Rate ◽  
Electromagnetic Signals

Abstract Gravitational wave (GW) signals from compact binary coalescences can be used as standard sirens to constrain cosmological parameters if its redshift can be measured independently by electromagnetic signals. However, mergers of stellar binary black holes (BBHs) may not have electromagnetic counterparts and thus have no direct redshift measurements. These dark sirens may be still used to statistically constrain cosmological parameters by combining their GW measured luminosity distances and localization with deep redshift surveys of galaxies around it. We investigate this dark siren method to constrain cosmological parameters in details by using mock BBH and galaxy samples. We find that the Hubble constant can be well constrained with an accuracy $\lesssim 1\%$ with a few tens or more BBH mergers at redshift up to $1$ if GW observations can provide accurate estimates of its luminosity distance (with relative error of $\lesssim 0.01$) and localization ($\lesssim 0.1\mathrm{deg}^2$), though the constraint may be significantly biased if the luminosity distance and localization errors are larger. We further generate mock BBH samples, according to current constraints on BBH merger rate and the distributions of BBH properties, and find that Deci-Hertz Observatory (DO) in a half year observation period may detect about one hundred BBHs with signal-to-noise ratio $\varrho \gtrsim 30$, relative luminosity distance error $\lesssim 0.02$, and localization error $\lesssim 0.01\mathrm{deg}^2$. By applying the dark standard siren method, we find that the Hubble constant can be constrained to $\sim 0.1-1\%$ level using these DO BBHs, an accuracy comparable to the constraints obtained by using electromagnetic observations in the near future, thus it may provide insight into the Hubble tension. We also demonstrate that the constraint on the Hubble constant using this dark siren method are robust and do not depend on the choice of the prior for the properties of BBH host galaxies.

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