scholarly journals Intermediate-mass black holes from stellar mergers in young star clusters

2021 ◽  
Vol 507 (4) ◽  
pp. 5132-5143
Author(s):  
Ugo N Di Carlo ◽  
Michela Mapelli ◽  
Mario Pasquato ◽  
Sara Rastello ◽  
Alessandro Ballone ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Clusters ◽  
Mass Range ◽  
Young Star ◽  
Intermediate Mass ◽  
Stellar Collisions ◽  
Low Metallicity ◽  
Young Star Clusters ◽  
Stellar Mergers ◽  
Intermediate Mass Black Holes

ABSTRACT Intermediate-mass black holes (IMBHs) in the mass range $10^2\!-\!10^5\, \mathrm{M_{\odot }}$ bridge the gap between stellar black holes (BHs) and supermassive BHs. Here, we investigate the possibility that IMBHs form in young star clusters via runaway collisions and BH mergers. We analyse 104 simulations of dense young star clusters, featuring up-to-date stellar wind models and prescriptions for core collapse and (pulsational) pair instability. In our simulations, only nine IMBHs out of 218 form via binary BH mergers, with a mass ∼100–140 M⊙. This channel is strongly suppressed by the low escape velocity of our star clusters. In contrast, IMBHs with masses up to ∼438 M⊙ efficiently form via runaway stellar collisions, especially at low metallicity. Up to ∼0.2 per cent of all the simulated BHs are IMBHs, depending on progenitor’s metallicity. The runaway formation channel is strongly suppressed in metal-rich (Z = 0.02) star clusters, because of stellar winds. IMBHs are extremely efficient in pairing with other BHs: ∼70 per cent of them are members of a binary BH at the end of the simulations. However, we do not find any IMBH–BH merger. More massive star clusters are more efficient in forming IMBHs: ∼8 per cent (∼1 per cent) of the simulated clusters with initial mass 104–3 × 104 M⊙ (103–5 × 103 M⊙) host at least one IMBH.

scholarly journals Intermediate-mass Black Holes from High Massive-star Binary Fractions in Young Star Clusters

2021 ◽  
Vol 908 (2) ◽  
pp. L29 ◽  
Author(s):  
Elena González ◽  
Kyle Kremer ◽  
Sourav Chatterjee ◽  
Giacomo Fragione ◽  
Carl L. Rodriguez ◽  
...  
Keyword(s):  
Black Holes ◽  
Massive Star ◽  
Star Clusters ◽  
Young Star ◽  
Intermediate Mass ◽  
Star Binary ◽  
Young Star Clusters ◽  
Intermediate Mass Black Holes

scholarly journals Collisions in primordial star clusters

2018 ◽  
Vol 614 ◽  
pp. A14 ◽  
Author(s):  
B. Reinoso ◽  
D. R. G. Schleicher ◽  
M. Fellhauer ◽  
R. S. Klessen ◽  
T. C. N. Boekholt
Keyword(s):  
Black Holes ◽  
Massive Stars ◽  
Star Clusters ◽  
Parameter Study ◽  
Effective Parameters ◽  
Intermediate Mass ◽  
Stellar Collisions ◽  
Accretion Rates ◽  
Relevant Role ◽  
Intermediate Mass Black Holes

Collisions were suggested to potentially play a role in the formation of massive stars in present day clusters, and have likely been relevant during the formation of massive stars and intermediate mass black holes within the first star clusters. In the early Universe, the first stellar clusters were particularly dense, as fragmentation typically only occurred at densities above 109 cm−3, and the radii of the protostars were enhanced as a result of larger accretion rates, suggesting a potentially more relevant role of stellar collisions. We present here a detailed parameter study to assess how the number of collisions and the mass growth of the most massive object depend on the properties of the cluster. We also characterize the time evolution with three effective parameters: the time when most collisions occur, the duration of the collisions period, and the normalization required to obtain the total number of collisions. We apply our results to typical Population III (Pop. III) clusters of about 1000 M⊙, finding that a moderate enhancement of the mass of the most massive star by a factor of a few can be expected. For more massive Pop. III clusters as expected in the first atomic cooling halos, we expect a more significant enhancement by a factor of 15–32. We therefore conclude that collisions in massive Pop. III clusters were likely relevant to form the first intermediate mass black holes.

scholarly journals Binary black holes in the pair instability mass gap

2020 ◽  
Vol 497 (1) ◽  
pp. 1043-1049 ◽  
Author(s):  
Ugo N Di Carlo ◽  
Michela Mapelli ◽  
Yann Bouffanais ◽  
Nicola Giacobbo ◽  
Filippo Santoliquido ◽  
...  
Keyword(s):  
Black Holes ◽  
Formation Rate ◽  
Star Clusters ◽  
Design Sensitivity ◽  
Young Star ◽  
Binary Black Holes ◽  
Single Star ◽  
Mass Gap ◽  
Young Star Clusters ◽  
Stellar Mergers

ABSTRACT Pair instability (PI) and pulsational PI prevent the formation of black holes (BHs) with mass ≳60 M⊙ from single star evolution. Here, we investigate the possibility that BHs with mass in the PI gap form via stellar mergers and multiple stellar mergers, facilitated by dynamical encounters in young star clusters. We analyse 104 simulations, run with the direct N-body code nbody6++gpu coupled with the population synthesis code mobse. We find that up to ∼6 per cent of all simulated BHs have mass in the PI gap, depending on progenitor’s metallicity. This formation channel is strongly suppressed in metal-rich (Z = 0.02) star clusters because of stellar winds. BHs with mass in the PI gap are initially single BHs but can efficiently acquire companions through dynamical exchanges. We find that ∼21 per cent, 10 per cent, and 0.5 per cent of all binary BHs have at least one component in the PI mass gap at metallicity Z = 0.0002, 0.002, and 0.02, respectively. Based on the evolution of the cosmic star formation rate and metallicity, and under the assumption that all stars form in young star clusters, we predict that ∼5 per cent of all binary BH mergers detectable by advanced LIGO and Virgo at their design sensitivity have at least one component in the PI mass gap.

Growth of intermediate mass black holes in first star clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 220-223
Author(s):  
Yuya Sakurai ◽  
Naoki Yoshida ◽  
Michiko S. Fujii
Keyword(s):  
Black Holes ◽  
Large Scale ◽  
Star Clusters ◽  
Star Cluster ◽  
Galaxy Mergers ◽  
Intermediate Mass ◽  
Tidal Disruption ◽  
Stellar Collisions ◽  
Gas Supply ◽  
Intermediate Mass Black Holes

AbstractWe study runaway stellar collisions in primordial star clusters and formation of intermediate mass black holes (IMBHs). Using cosmological simulations, we identify eight atomic-cooling halos in which the star clusters form. We follow stellar and dark matter (DM) dynamics for 3Myr using hybrid N-body simulations. We find that the runaway stellar collisions occur in all star clusters and IMBHs with masses ∼400–1900M⊙ form. Performing additional N-body simulations, we explore evolutions of the IMBHs in the star clusters for 15 Myr. The IMBH masses grow via stellar tidal disruption events (TDEs) to ∼700–2500 M⊙. The TDE rates are ∼0.3–1.3 Myr−1. DM motions affect the star cluster evolutions and reduce the TDE rates. The IMBHs may subsequently grow to SMBHs by gas supply through galaxy mergers or large-scale gas inflows, or they may remain within or around the clusters.

scholarly journals The Ecology of Star Clusters and Intermediate‐Mass Black Holes in the Galactic Bulge

2006 ◽  
Vol 641 (1) ◽  
pp. 319-326 ◽  
Author(s):  
Simon F. Portegies Zwart ◽  
Holger Baumgardt ◽  
Stephen L. W. McMillan ◽  
Junichiro Makino ◽  
Piet Hut ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Clusters ◽  
Galactic Bulge ◽  
Intermediate Mass ◽  
Intermediate Mass Black Holes

scholarly journals EFFECTS OF INTERMEDIATE MASS BLACK HOLES ON NUCLEAR STAR CLUSTERS

2014 ◽  
Vol 796 (1) ◽  
pp. 40 ◽  
Author(s):  
Alessandra Mastrobuono-Battisti ◽  
Hagai B. Perets ◽  
Abraham Loeb
Keyword(s):  
Black Holes ◽  
Star Clusters ◽  
Intermediate Mass ◽  
Intermediate Mass Black Holes

scholarly journals Monte Carlo modeling of globular star clusters: many primordial binaries and IMBH formation

2014 ◽  
Vol 10 (S312) ◽  
pp. 213-222
Author(s):  
Mirek Giersz ◽  
Nathan Leigh ◽  
Michael Marks ◽  
Arkadiusz Hypki ◽  
Abbas Askar
Keyword(s):  
Black Holes ◽  
Monte Carlo ◽  
Black Hole ◽  
Star Clusters ◽  
Orbital Parameter ◽  
Intermediate Mass ◽  
Cluster Evolution ◽  
Global Cluster ◽  
Cluster Properties ◽  
Intermediate Mass Black Holes

AbstractWe will discuss the evolution of star clusters with a large initial binary fraction, up to 95%. The initial binary population is chosen to follow the invariant orbital-parameter distributions suggested by Kroupa (1995). The Monte Carlo MOCCA simulations of star cluster evolution are compared to the observations of Milone et al. (2012) for photometric binaries. It is demonstrated that the observed dependence on cluster mass of both the binary fraction and the ratio of the binary fractions inside and outside of the half mass radius are well recovered by the MOCCA simulations. This is due to a rapid decrease in the initial binary fraction due to the strong density-dependent destruction of wide binaries described by Marks, Kroupa & Oh (2011). We also discuss a new scenario for the formation of intermediate mass black holes in dense star clusters. In this scenario, intermediate mass black holes are formed as a result of dynamical interactions of hard binaries containing a stellar mass black hole, with other stars and binaries. We will discuss the necessary conditions to initiate the process of intermediate mass black hole formation and the dependence of its mass accretion rate on the global cluster properties.

scholarly journals Wandering off the centre: a characterization of the random motion of intermediate-mass black holes in star clusters

2017 ◽  
Vol 475 (2) ◽  
pp. 1574-1586 ◽  
Author(s):  
Ruggero de Vita ◽  
Michele Trenti ◽  
Morgan MacLeod
Keyword(s):  
Black Holes ◽  
Star Clusters ◽  
Random Motion ◽  
Intermediate Mass ◽  
Intermediate Mass Black Holes

scholarly journals HST's hunt for intermediate-mass black holes in star clusters

2009 ◽  
Vol 5 (S266) ◽  
pp. 231-237 ◽  
Author(s):  
Julio Chanamé ◽  
Justice Bruursema ◽  
Rupali Chandar ◽  
Jay Anderson ◽  
Roeland van der Marel ◽  
...  
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Dynamical Analysis ◽  
Intermediate Mass ◽  
Data Set ◽  
Upper Limits ◽  
Intermediate Mass Black Holes

AbstractEstablishing or ruling out, either through solid mass measurements or upper limits, the presence of intermediate-mass black holes (IMBHs; with masses of 102 − 105 M⊙) at the centers of star clusters would profoundly impact our understanding of problems ranging from the formation and long-term dynamical evolution of stellar systems, to the nature of the seeds and the growth mechanisms of supermassive black holes. While there are sound theoretical arguments both for and against their presence in today's clusters, observational studies have so far not yielded truly conclusive IMBH detections nor upper limits. We argue that the most promising approach to solving this issue is provided by the combination of measurements of the proper motions of stars at the centers of Galactic globular clusters and dynamical models able to take full advantage of this type of data set. We present a program based on HST observations and recently developed tools for dynamical analysis designed to do just that.

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.

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