scholarly journals Evolution of binary supermassive black holes and the final-parsec problem

2014 ◽  
Vol 10 (S312) ◽  
pp. 92-100
Author(s):  
Eugene Vasiliev
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Asymptotic Behavior ◽  
Supermassive Black Holes ◽  
Stellar Systems ◽  
Supermassive Black Hole ◽  
The Galaxy ◽  
Collisionless Regime ◽  
Wave Emission ◽  
Number Of Particles

AbstractI review the evolution of binary supermassive black holes and focus on the stellar-dynamical mechanisms that may help to overcome the final-parsec problem – the possible stalling of the binary at a separation much larger than is required for an efficient gravitational wave emission. RecentN-body simulations have suggested that a departure from spherical symmetry in the nucleus of the galaxy may keep the rate of interaction of stars with the binary at a high enough level so that the binary continues to shrink rather rapidly. However, a major problem of all these simulations is that they do not probe the regime where collisionless effects are dominant – in other words, the number of particles in the simulation is still not sufficient to reach the asymptotic behavior of the system. I present a novel Monte Carlo method for simulating both collisional and collisionless evolution of non-spherical stellar systems, and apply it for the problem of binary supermassive black hole evolution. I show that in triaxial galaxies the final-parsec problem is largely non-existent, while in the axisymmetric case it seems to still exist in the limit of purely collisionless regime relevant for real galaxies, but disappears in theN-body simulations where the feasible values ofNare still too low to get rid of collisional effects.

scholarly journals The ecology of the galactic centre: Nuclear stellar clusters and supermassive black holes

2019 ◽  
Vol 14 (S351) ◽  
pp. 80-83 ◽  
Author(s):  
Melvyn B. Davies ◽  
Abbas Askar ◽  
Ross P. Church
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Large Fraction ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Galactic Centre ◽  
Stellar Clusters ◽  
Stellar Cluster ◽  
Supermassive Black Hole ◽  
Multiple Clusters

AbstractSupermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these clusters contain a single intermediate-mass black hole (IMBH). In the cases where multiple clusters contain IMBHs, we discuss whether the black holes are likely to merge and whether such mergers are likely to result in the ejection of the merged black hole from the nuclear stellar cluster. In some cases, no supermassive black hole will form as any merger product is not retained. This is a natural pathway to explain those galactic nuclei that contain a nuclear stellar cluster but apparently lack a supermassive black hole; M33 being a nearby example. Alternatively, if an IMBH merger product is retained within the nuclear stellar cluster, it may subsequently grow, e.g. via the tidal disruption of stars, to form a supermassive black hole.

Determination of supermassive black hole spins in active galactic nuclei

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040054
Author(s):  
M. Yu. Piotrovich ◽  
V. L. Afanasiev ◽  
S. D. Buliga ◽  
T. M. Natsvlishvili
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Disk Model ◽  
Supermassive Black Hole

Based on spectropolarimetry for a number of active galactic nuclei in Seyfert 1 type galaxies observed with the 6-m BTA telescope, we have estimated the spins of the supermassive black holes at the centers of these galaxies. We have determined the spins based on the standard Shakura-Sunyaev accretion disk model. More than 70% of the investigated active galactic nuclei are shown to have Kerr supermassive black holes with a dimensionless spin greater than 0.9.

scholarly journals 11.1. Black holes and galaxy centers

1998 ◽  
Vol 184 ◽  
pp. 451-458 ◽  
Author(s):  
Douglas Richstone
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Central Black Hole ◽  
The Core ◽  
Supermassive Black Hole ◽  
Normal Galaxy ◽  
The Galaxy ◽  
Major Review

The study of supermassive galactic black holes (BH) has moved beyond discovery to maturity. The are now ∼ 15 reliable detections. The mass of a central black hole apparently correlates with the mass of the hot component of its galactic host. It may be that every normal galaxy has a supermassive black hole carrying about 10−3 of its bulge mass, with important consequences for the structure and evolution of the core of the galaxy. The most recent major review is by Kormendy & Richstone (1995, KR).

Formation history of supermassive black holes in a viable cosmological window

2006 ◽  
Vol 2 (S238) ◽  
pp. 345-346
Author(s):  
Carlos H. Coimbra-Araújo ◽  
Amâncio C. S. Friaça
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Supermassive Black Holes ◽  
Intermediate Mass ◽  
Disk Model ◽  
Rapid Rotation ◽  
Supermassive Black Hole ◽  
Formation History ◽  
History Of ◽  
Stable Part

AbstractWe show, performing a viable cosmological window, that only the magneto hydrodynamic (MHD) disk model is capable to explain how an intermediate mass black hole (IMBH) (with masses ∼ 103M⊙) grows unto a supermassive black hole (SMBH) (with masses ∼ 107M⊙). We still calculate the supermassive stars sequence of stability. Those stars, with synthetized helium or oxygen cores, collapse to form IMBHs. In our calculation we show that the primordial stars must have rapid rotation if they are in the stable part of the sequence.

scholarly journals Evolution of Merger Remnants with Supermassive Black Holes

2003 ◽  
Vol 208 ◽  
pp. 455-456
Author(s):  
Jeremy Tinker ◽  
Barbara Ryden
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Numerical Simulations ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Supermassive Black Holes ◽  
Host Galaxies ◽  
Supermassive Black Hole

We present results of numerical simulations of mergers of spiral galaxies using GADGET (Springel, Yoshida, & White 2001). In three of these simulations one of the progenitor galaxies contained a central supermassive black hole (BH), as well as one simulation which did not contain a BH. The merger remnants were evolved to an age of ∼ 13 Gyr to examine the evolution of the shape of each merger remnant. The results of these simulations were compared to observations of elliptical galaxies, which show that older galaxies appear rounder than younger ones (Ryden, Forbes, & Terlevich 2001).We found that the simulations in which the BH mass was fixed throughout the evolution influence the shape of their host galaxies on timescales less than 3 Gyr. These simulations show little trend of shape with age beyond this time. In the simulations in which the BH mass increased linearly over the duration of the simulation, there is a significant evolution of the shape of the remnant throughout its lifetime, comparable to the observational trend.

scholarly journals Brownian motion of supermassive black holes in galaxy cores

2019 ◽  
Vol 14 (S351) ◽  
pp. 93-96 ◽  
Author(s):  
Pierfrancesco Di Cintio ◽  
Luca Ciotti ◽  
Carlo Nipoti
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
Stochastic Noise ◽  
Stellar Clusters ◽  
Dynamical Friction ◽  
Intermediate Mass ◽  
System Parameters ◽  
The Galaxy ◽  
Galaxy Cores ◽  
Number Of Particles

AbstractWe investigate the dynamics of supermassive black holes (SMBHs) in galactic cores by means of a semi-analytic model based on the Langevin equation, including dynamical friction and stochastic noise accounting for the gravitational interactions with stars. The model is validated against direct N-body simulations of intermediate-mass black holes in stellar clusters where a realistic number of particles is accessible. For the galactic case, we find that the SMBH experiences a Brownian-like motion with a typical displacement from the geometric center of the Galaxy of a few parsecs, for system parameters compatible with M87.

The effects of outbursts from Supermassive Black Holes: A close look at M87

2019 ◽  
Vol 15 (S359) ◽  
pp. 99-107
Author(s):  
C. Jones ◽  
W. Forman
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Fossil Record ◽  
Virgo Cluster ◽  
Supermassive Black Holes ◽  
Article Title ◽  
X Ray ◽  
Hot Gas ◽  
Supermassive Black Hole ◽  
Evolution Of Galaxies

AbstractSupermassive black holes (SMBHs) play[-105pt]Kindly check and confirm the Article Title. fundamental roles in the evolution of galaxies, groups, and clusters. The fossil record of supermassive black hole outbursts is seen through the cavities and shocks that are imprinted on these gas-rich systems. For M87, the central galaxy in the Virgo cluster, deep Chandra observations illustrate the physics of AGN feedback in hot, gas-rich atmospheres and allow measurements of the age, duration, and power of the outburst from the supermassive black hole in M87 that produced the observed cavities and shocks in the hot X-ray atmosphere.

scholarly journals Investigation of some galactic and extragalactic gravitational phenomena

2012 ◽  
pp. 1-16 ◽  
Author(s):  
P. Jovanovic
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Accretion Disk ◽  
Supermassive Black Holes ◽  
Bright Spot ◽  
Kerr Metric ◽  
Massive Black Hole ◽  
Spacetime Geometry ◽  
Supermassive Black Hole

Here we present a short overview of the most important results of our investigations of the following galactic and extragalactic gravitational phenomena: supermassive black holes in centers of galaxies and quasars, supermassive black hole binaries, gravitational lenses and dark matter. For the purpose of these investigations, we developed a model of a relativistic accretion disk around a supermassive black hole, based on the ray-tracing method in the Kerr metric, a model of a bright spot in an accretion disk and three different models of gravitational microlenses. All these models enabled us to study physics, spacetime geometry and effects of strong gravity in the vicinity of supermassive black holes, variability of some active galaxies and quasars, different effects in the lensed quasars with multiple images, as well as the dark matter fraction in the Universe. We also found an observational evidence for the first spectroscopically resolved sub-parsec orbit of a supermassive black hole binary system in the core of active galaxy NGC 4151. Besides, we studied applications of one potential alternative to dark matter in the form of a modified theory of gravity on Galactic scales, to explain the recently observed orbital precession of some S-stars, which are orbiting around a massive black hole at the Galactic center.

scholarly journals Study of Periodic Signals from Blazars

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 15
Author(s):  
Gopal Bhatta
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gamma Ray ◽  
Supermassive Black Holes ◽  
Light Curves ◽  
Supermassive Black Hole ◽  
Transient Nature ◽  
Time Series Analyses ◽  
Periodic Signals

The search for periodic signals from blazars has become an actively pursued field of research in recent years. This is because periodic signals bring us information about the processes occurring near the innermost regions of blazars, which are mostly inaccessible to our direct view. Such signals provide insights into some of the extreme conditions that take place in the vicinity of supermassive black holes that lead to the launch of the relativistic jets. In addition, studies of characteristic timescales in blazar light curves shed light on some of the challenging issues in blazar physics that include disk-jet connection, strong gravity near fast-rotating supermassive black holes and release of gravitational waves from binary supermassive black hole systems. However, a number of issues associated with the search for quasi-periodic oscillations (QPOs) in blazars e.g., red-noise dominance, modest significance of the detection, periodic modulation lasting for only a couple of cycles and their transient nature, make it difficult to estimate the true significance of the detection. Consequently, it also becomes difficult to make meaningful inferences about the nature of the on-going processes. In this proceedings, results of study focused on searching for QPOs in a number of blazar multi-frequency light curves are summarized. The time series analyses of long term observations of the blazars revealed the presence of year-timescale QPOs in the sources including OJ 287 (optical), Mrk 501 (gamma-ray), J1043+2408 (radio) and PKS 0219-164 (radio). A likely explanations, we discuss a number of scenarios including binary supermassive black hole systems, lense-thirring precession, and jet precession.

scholarly journals Very extreme mass-ratio bursts in the Galaxy and neighbouring galaxies in relation to space-borne detectors

2020 ◽  
Vol 498 (1) ◽  
pp. L61-L65
Author(s):  
Wen-Biao Han ◽  
Xing-Yu Zhong ◽  
Xian Chen ◽  
Shuo Xin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Brown Dwarfs ◽  
Compact Objects ◽  
Primordial Black Holes ◽  
Mass Ratio ◽  
Supermassive Black Hole ◽  
Future Space ◽  
The Galaxy ◽  
Event Rates

ABSTRACT Two recent papers (by Amaro-Seoane andGourgoulhon and co-workers) revealed that in our Galaxy there are very extreme mass-ratio inspirals composed of brown dwarfs and a supermassive black hole at the centre of the Galaxy. The event rates estimated in these papers are very considerable for future space-borne detectors. In addition, there are plunge events during the formation of inspiralling orbits. In this work, we calculate the gravitational waves from compact objects (brown dwarfs, primordial black holes, etc.) plunging into or being scattered by the central supermassive black hole. We find that for space-borne detectors the signal-to-noise ratios of these bursts are quite high. The event rates are estimated as ∼ 0.01 yr–1 for the Galaxy. If we are lucky, this kind of very extreme mass-ratio burst will offer a unique chance to reveal the nearest supermassive black hole and nuclei dynamics. The event rate could be as large as 4∼8 yr–1 within 10 Mpc, and because the signal is strong enough for observations by space-borne detectors, we have a good chance of being able to probe the nature of neighbouring black holes.

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