scholarly journals Monte Carlo simulations of black hole mergers in AGN discs: Low χeff mergers and predictions for LIGO

2020 ◽  
Vol 494 (1) ◽  
pp. 1203-1216 ◽  
Author(s):  
B McKernan ◽  
K E S Ford ◽  
R O’Shaugnessy ◽  
D Wysocki
Keyword(s):  
Black Holes ◽  
Monte Carlo ◽  
Black Hole ◽  
Monte Carlo Simulations ◽  
First Generation ◽  
Accretion Discs ◽  
Spin Distribution ◽  
Mass Ratios ◽  
Merger Rate ◽  
Hubble Time

ABSTRACT Accretion discs around supermassive black holes are promising sites for stellar mass black hole mergers detectable with LIGO. Here we present the results of Monte Carlo simulations of black hole mergers within 1-d AGN disc models. For the spin distribution in the disc bulk, key findings are: (1) The distribution of χeff is naturally centred around $\tilde{\chi }_{\rm eff} \approx 0.0$, (2) the width of the χeff distribution is narrow for low natal spins. For the mass distribution in the disc bulk, key findings are: (3) mass ratios $\tilde{q} \sim 0.5\!-\!0.7$, (4) the maximum merger mass in the bulk is $\sim 100\!-\!200\, \mathrm{M}_{\odot }$, (5) $\sim 1{{\ \rm per\ cent}}$ of bulk mergers involve BH $\gt 50\, \mathrm{M}_{\odot }$ with (6) $\simeq 80{{\ \rm per\ cent}}$ of bulk mergers are pairs of first generation BH. Additionally, mergers at a migration trap grow an IMBH with typical merger mass ratios $\tilde{q}\sim 0.1$. Ongoing LIGO non-detections of black holes $\gt 10^{2}\, \mathrm{M}_{\odot }$ puts strong limits on the presence of migration traps in AGN discs (and therefore AGN disc density and structure) as well as median AGN disc lifetime. The highest merger rate occurs for this channel if AGN discs are relatively short-lived (≤1 Myr) so multiple AGN episodes can happen per Galactic nucleus in a Hubble time.

scholarly journals The Merger Rate of Black Holes in a Primordial Black Hole Cluster

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 372-378
Author(s):  
Viktor D. Stasenko ◽  
Alexander A. Kirillov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Star Clusters ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Central Black Hole ◽  
Solar Mass ◽  
Merger Rate

In this paper, the merger rate of black holes in a cluster of primordial black holes (PBHs) is investigated. The clusters have characteristics close to those of typical globular star clusters. A cluster that has a wide mass spectrum ranging from 10−2 to 10M⊙ (Solar mass) and contains a massive central black hole of the mass M•=103M⊙ is considered. It is shown that in the process of the evolution of cluster, the merger rate changed significantly, and by now, the PBH clusters have passed the stage of active merging of the black holes inside them.

scholarly journals X-Ray Heated Accretion Discs Around Stellar Mass Black Holes

2004 ◽  
Vol 194 ◽  
pp. 200-201
Author(s):  
Ivan Hubeny ◽  
Dayal T. Wickramasinghe
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Vertical Structure ◽  
Black Body ◽  
Incident Radiation ◽  
Accretion Discs ◽  
Distribution Models ◽  
Solar Mass ◽  
X Ray ◽  
Low Mass

We investigate the effects of irradiation on the vertical structure of accretion discs around black holes and its impact on the emergent energy distribution. Models are presented for a 10 Solar mass black hole in a low mass X-ray binary assuming a black body spectrum for the incident radiation. We show that for a disc annulus at a given radius, the spectra become increasingly distorted as the incident flux increases relative to the viscously generated heating flux in the disc. Significant effects are apparent for rings even at distances of ~ 10,000 Schwarzschild radii from the black hole for realistic dilution factors.

scholarly journals Two New Possible Mechanisms of Supernova-Like Explosions

2005 ◽  
Vol 192 ◽  
pp. 263-268
Author(s):  
V.V. Tikhomirov ◽  
S.E. Yuralevich
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Final Stage ◽  
White Dwarfs ◽  
Primordial Black Holes ◽  
Considerable Part ◽  
Nuclear Burning ◽  
Urca Process ◽  
Hubble Time

SummaryPrimordial black holes (PBHs) of microscopical size can completely absorb neutron stars (NSs) and white dwarfs (WDs) for less than the Hubble time. NS absorption is accompanied by inverse URCA process giving rise to emission of antineutrino. However considerable part of these antineutrino fails to escape NS being drawn into the growing black hole by accreting NS matter. The final stage of dense WD absorption is accompanied by 1051 erg neutrino burst able to ignite nuclear burning giving rise to supernova-like WD explosion.

scholarly journals Monte Carlo Simulations of the 2+1 Dimensional Fokker-Planck Equation: Spherical Star Clusters Containing Massive, Central Black Holes

1985 ◽  
Vol 113 ◽  
pp. 373-413 ◽  
Author(s):  
Stuart L. Shapiro
Keyword(s):  
Black Holes ◽  
Monte Carlo ◽  
Black Hole ◽  
Phase Space ◽  
Star Clusters ◽  
Galactic Nuclei ◽  
Planck Equation ◽  
Time Dependent ◽  
Central Black Hole ◽  
Fokker Planck Equation

The dynamical behavior of a relaxed star cluster containing a massive, central black hole poses a challenging problem for the theorist and intriguing possibilities for the observer. The historical development of the subject is sketched and the salient features of the physical solution and its observational consequences are summarized.The full dynamical problem of a relaxed, self-gravitating, large N-body system containing a massive central black hole has all the necessary ingredients to excite the most dispassionate many-body, computational physicist: it is a time-dependent, multidimensional, nonlinear problem which must be solved over widely disparate length and time scales simultaneously. The problem has been tackled at various levels of approximation over the years. A new 2+1 dimensional Monte Carlo simulation code has been developed in appreciable generality to solve the time-dependent Fokker-Planck equation in E-J space for this problem. The code incorporates such features as (1) a particle “cloning and renormalization” scheme to provide a statistically reliable population of test particles in low density regions of phase space and (2) a time-step “adjustment” algorithm to ensure integration on local relaxation timescales without having to follow typical particles on orbital trajectories. However, critical regions in phase space (e.g. disruption “loss-cone” trajectories) can still be followed on orbital timescales. Numerical results obtained with this Monte Carlo scheme for the dynamical structure and evolution of globular star clusters and dense galactic nuclei containing massive black holes are reviewed.Recent dynamical integrations of the Einstein field equations for spherical, collisionless (Vlasov) systems in General Relativity suggest a possible origin for the supermassive black holes believed to power quasars and active galactic nuclei. This scenario is discussed briefly.

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 The Role of Gravitational Instabilities in the Feeding of Supermassive Black Holes

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Giuseppe Lodato
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Redshift ◽  
Supermassive Black Holes ◽  
Point Of View ◽  
Accretion Discs ◽  
Theoretical Point ◽  
Interstellar Gas ◽  
Massive Black Hole

I review the recent progresses that have been obtained, especially through the use of high-resolution numerical simulations, on the dynamics of self-gravitating accretion discs. A coherent picture is emerging, where the disc dynamics is controlled by a small number of parameters that determine whether the disc is stable or unstable, whether the instability saturates in a self-regulated state or runs away into fragmentation, and whether the dynamics is local or global. I then apply these concepts to the case of AGN discs, discussing the implications of such evolution on the feeding of supermassive black holes. Nonfragmenting, self-gravitating discs appear to play a fundamental role in the process of formation of massive black hole seeds at high redshift ( 10–15) through direct gas collapse. On the other hand, the different cooling properties of the interstellar gas at low redshifts determine a radically different behaviour for the outskirts of the accretion discs feeding typical AGNs. Here the situation is much less clear from a theoretical point of view, and while several observational clues point to the important role of massive discs at a distance of roughly a parsec from their central black hole, their dynamics is still under debate.

scholarly journals Thermal spectra of thin accretion discs of finite thickness around Kerr black holes

2020 ◽  
Vol 496 (1) ◽  
pp. 497-503 ◽  
Author(s):  
Menglei Zhou ◽  
Askar B Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Victoria Grinberg ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Finite Thickness ◽  
Kerr Black Hole ◽  
Accretion Discs ◽  
Black Hole Mass ◽  
New Model ◽  
Fitting Method ◽  
Black Hole Binary ◽  
The Difference

ABSTRACT The analysis of the thermal spectrum of geometrically thin and optically thick accretion discs of black holes, the so-called continuum-fitting method, is one of the leading techniques for measuring black hole spins. Current models normally approximate the disc as infinitesimally thin, while in reality the disc thickness is finite and increases as the black hole mass accretion rate increases. Here we present an XSPEC model to calculate the multitemperature blackbody spectrum of a thin accretion disc of finite thickness around a Kerr black hole. We test our new model with an RXTE observation of the black hole binary GRS 1915+105. We find that the spin value inferred with the new model is slightly higher than the spin value obtained with a model with an infinitesimally thin disc, but the difference is small and the effect is currently subdominant with respect to other sources of uncertainties in the final spin measurement.

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