scholarly journals Gravitational loss-cone instability in stellar clusters around massive black holes

2007 ◽  
Vol 3 (S245) ◽  
pp. 255-256
Author(s):  
Evgeny V. Polyachenko ◽  
Valerij L. Polyachenko ◽  
Ilia G. Shukhman
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Thin Disk ◽  
Stellar Clusters ◽  
Loss Cone ◽  
Massive Black Holes ◽  
Angular Momenta

AbstractStability of spherical and thin disk stellar clusters surrounding massive black holes are studied. Due to the black hole, stars with sufficiently low angular momenta escape from the system through the loss cone. We show that stability of spherical clusters crucially depend on whether the distribution of stars is monotonic or non-monotonic in angular momentum. It turns out that only non-monotonic distributions can be unstable. At the same time the instability in disk clusters is possible for both types of distributions.

scholarly journals Gaseous Disks in the Nuclei of Elliptical Galaxies

1997 ◽  
Vol 163 ◽  
pp. 620-625 ◽  
Author(s):  
H. Ford ◽  
Z. Tsvetanov ◽  
L. Ferrarese ◽  
G. Kriss ◽  
W. Jaffe ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Accretion Disks ◽  
Large Scale ◽  
Elliptical Galaxies ◽  
Central Mass ◽  
Massive Black Holes ◽  
Radio Jets

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.

scholarly journals Energy and angular momentum in D-dimensional Kerr-Ads black holes — New formulation

2021 ◽  
pp. 2150201
Author(s):  
Emel Altas
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Einstein Metrics ◽  
Riemann Tensor ◽  
De Sitter ◽  
Gauge Invariant ◽  
Angular Momenta ◽  
Ads Black Holes ◽  
New Formulation

Recently, it was shown that the conserved charges of asymptotically anti-de Sitter spacetimes can be written in an explicitly gauge-invariant way in terms of the linearized Riemann tensor and the Killing vectors. Here, we employ this construction to compute the mass and angular momenta of the [Formula: see text]-dimensional Kerr-AdS black holes, which is one of the most remarkable Einstein metrics generalizing the four-dimensional rotating black hole.

scholarly journals Coalescence of Kerr Black Holes—Binary Systems from GW150914 to GW170814

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1017
Author(s):  
Bogeun Gwak
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Gravitational Wave ◽  
Orbital Angular Momentum ◽  
Binary Systems ◽  
Analytical Form ◽  
Angular Momenta ◽  
Binary Black Hole ◽  
Kerr Black Holes

We investigate the energy of the gravitational wave from a binary black hole merger by the coalescence of two Kerr black holes with an orbital angular momentum. The coalescence is constructed to be consistent with particle absorption in the limit in which the primary black hole is sufficiently large compared with the secondary black hole. In this limit, we analytically obtain an effective gravitational spin–orbit interaction dependent on the alignments of the angular momenta. Then, binary systems with various parameters including equal masses are numerically analyzed. According to the numerical analysis, the energy of the gravitational wave still depends on the effective interactions, as expected from the analytical form. In particular, we ensure that the final black hole obtains a large portion of its spin angular momentum from the orbital angular momentum of the initial binary black hole. To estimate the angular momentum released by the gravitational wave in the actual binary black hole, we apply our results to observations at the Laser Interferometer Gravitational-Wave Observatory: GW150914, GW151226, GW170104, GW170608 and GW170814.

AGN fueling and feedback

2019 ◽  
Vol 15 (S356) ◽  
pp. 177-183
Author(s):  
Francoise Combes
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Active Galaxies ◽  
Escape Velocity ◽  
Black Hole Mass ◽  
Random Orientation ◽  
Massive Black Holes ◽  
Molecular Outflows ◽  
Sphere Of Influence

AbstractDynamical mechanisms are essential to exchange angular momentum in galaxies, drive the gas to the center, and fuel the central super-massive black holes. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching ∼10pc scale have revealed, within the sphere of influence of the black hole, smoking gun evidence of fueling. Observations of AGN feedback are described, together with the suspected responsible mechanisms. Molecular outflows are frequently detected in active galaxies with ALMA and NOEMA, with loading factors between 1 and 5. When driven by AGN with escape velocity, these outflows are therefore a clear way to moderate or suppress star formation. Molecular disks, or tori, are detected at 10pc-scale, kinematically decoupled from their host disk, with random orientation. They can be used to measure the black hole mass.

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.

scholarly journals X-ray properties of reverberation-mapped AGNs with super-Eddington accreting massive black holes

2019 ◽  
Vol 15 (S356) ◽  
pp. 143-143
Author(s):  
Jaya Maithil ◽  
Michael S. Brotherton ◽  
Bin Luo ◽  
Ohad Shemmer ◽  
Sarah C. Gallagher ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Rate ◽  
Time Lags ◽  
Black Hole Mass ◽  
Host Galaxies ◽  
Massive Black Holes ◽  
X Ray ◽  
Photon Index ◽  
The Impact

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.

scholarly journals Self-Regular Black Holes Quantized by means of an Analogue to Hydrogen Atoms

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Chang Liu ◽  
Yan-Gang Miao ◽  
Yu-Mei Wu ◽  
Yu-Hao Zhang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Density ◽  
Hydrogen Atoms ◽  
Quantum Black Hole ◽  
Extreme Black Hole ◽  
Angular Momenta ◽  
Probability Densities ◽  
Hoop Conjecture ◽  
Hole Model

We suggest a quantum black hole model that is based on an analogue to hydrogen atoms. A self-regular Schwarzschild-AdS black hole is investigated, where the mass density of the extreme black hole is given by the probability density of the ground state of hydrogen atoms and the mass densities of nonextreme black holes are given by the probability densities of excited states with no angular momenta. Such an analogue is inclined to adopt quantization of black hole horizons. In this way, the total mass of black holes is quantized. Furthermore, the quantum hoop conjecture and the Correspondence Principle are discussed.

Bound orbits around modified Hayward black holes

2021 ◽  
Author(s):  
Bo Gao ◽  
Xue-Mei Deng
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Gravitational Field ◽  
Periodic Orbits ◽  
Kerr Black Hole ◽  
Periodic Oscillations ◽  
Test Particles ◽  
Spin Parameter ◽  
Bound Orbits

The neutral time-like particle’s bound orbits around modified Hayward black holes have been investigated. We find that both in the marginally bound orbits (MBO) and the innermost stable circular orbits (ISCO), the test particle’s radius and its angular momentum are all more sensitive to one of the parameters [Formula: see text]. Especially, modified Hayward black holes with [Formula: see text] could mimic the same ISCO radius around the Kerr black hole with the spin parameter up to [Formula: see text]. Small [Formula: see text] could mimic the ISCO of small-spinning test particles around Schwarzschild black holes. Meanwhile, rational (periodic) orbits around modified Hayward black holes have also been studied. The epicyclic frequencies of the quasi-circular motion around modified Hayward black holes are calculated and discussed with respect to the observed Quasi-periodic oscillations (QPOs) frequencies. Our results show that rational orbits around modified Hayward black holes have different values of the energy from the ones of Schwarzschild black holes. The epicyclic frequencies in modified Hayward black holes have different frequencies from Schwarzschild and Kerr ones. These might provide hints for distinguishing modified Hayward black holes from Schwarzschild and Kerr ones by using the dynamics of time-like particles around the strong gravitational field.

scholarly journals The Sub-Eddington Boundary for the Quasar Mass–Luminosity Plane: A Theoretical Perspective

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 145 ◽  
Author(s):  
David Garofalo ◽  
Damian J. Christian ◽  
Andrew M. Jones
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Survey Data ◽  
Theoretical Perspective ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Massive Black Holes ◽  
Sky Survey ◽  
Data Release ◽  
Gap Paradigm

By exploring more than sixty thousand quasars from the Sloan Digital Sky Survey Data Release 5, Steinhardt & Elvis discovered a sub-Eddington boundary and a redshift-dependent drop-off at higher black hole mass, possible clues to the growth history of massive black holes. Our contribution to this special issue of Universe amounts to an application of a model for black hole accretion and jet formation to these observations. For illustrative purposes, we include ~100,000 data points from the Sloan Digital Sky Survey Data Release 7 where the sub-Eddington boundary is also visible and propose a theoretical picture that explains these features. By appealing to thin disk theory and both the lower accretion efficiency and the time evolution of jetted quasars compared to non-jetted quasars in our “gap paradigm”, we explain two features of the sub-Eddington boundary. First, we show that a drop-off on the quasar mass-luminosity plane for larger black hole mass occurs at all redshifts. But the fraction of jetted quasars is directly related to the merger function in this paradigm, which means the jetted quasar fraction drops with decrease in redshift, which allows us to explain a second feature of the sub-Eddington boundary, namely a redshift dependence of the slope of the quasar mass–luminosity boundary at high black hole mass stemming from a change in radiative efficiency with time. We are able to reproduce the mass dependence of, as well as the oscillating behavior in, the slope of the sub-Eddington boundary as a function of time. The basic physical idea involves retrograde accretion occurring only for a subset of the more massive black holes, which implies that most spinning black holes in our model are prograde accretors. In short, this paper amounts to a qualitative overview of how a sub-Eddington boundary naturally emerges in the gap paradigm.

Sign in / Sign up

Export Citation Format

Share Document