Forward Modeling Populations of Flares from Tidal Disruptions of Stars by Supermassive Black Holes

We study epicyclic oscillatory motion along circular geodesics of the Simpson–Visser meta-geometry describing in a unique way regular black-bounce black holes and reflection-symmetric wormholes by using a length parameter l. We give the frequencies of the orbital and epicyclic motion in a Keplerian disc with inner edge at the innermost circular geodesic located above the black hole outer horizon or on the our side of the wormhole. We use these frequencies in the epicyclic resonance version of the so-called geodesic models of high-frequency quasi-periodic oscillations (HF QPOs) observed in microquasars and around supermassive black holes in active galactic nuclei to test the ability of this meta-geometry to improve the fitting of HF QPOs observational data from the surrounding of supermassive black holes. We demonstrate that this is really possible for wormholes with sufficiently high length parameter l.

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Cosmological Evolution of Supermassive Black Holes: Mass Functions and Spins

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312019904 ◽

2012 ◽

Vol 8 (S290) ◽

pp. 259-260 ◽

Cited By ~ 1

Author(s):

Yan-Rong Li ◽

Jian-Min Wang ◽

Luis C. Ho

Keyword(s):

Black Holes ◽

Mass Function ◽

Supermassive Black Holes ◽

Cosmological Evolution ◽

Radiative Efficiency ◽

Bolometric Luminosity ◽

History Of ◽

Minor Mergers ◽

Mass Dependent ◽

Mass Functions

AbstractWe derive the mass function of supermassive black holes (SMBHs) over the redshift range 0 > z ≲ 2, using the latest deep luminosity and mass functions of field galaxies. Applying this mass function, combined with the bolometric luminosity function of active galactic nuclei (AGNs), into the the continuity equation of SMBH number density, we explicitly obtain the mass-dependent cosmological evolution of the radiative efficiency for accretion. We suggest that the accretion history of SMBHs and their spins evolve in two distinct regimes: an early phase of prolonged accretion, plausibly driven by major mergers, during which the black hole spins up, then switching to a period of random, episodic accretion, governed by minor mergers and internal secular processes, during which the hole spins down. The transition epoch depends on mass, mirroring other evidence for “cosmic downsizing” in the AGN population.

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319006689 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 80-83 ◽

Cited By ~ 1

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.

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2.4. Collisional stellar dynamics around a central galactic black hole

Symposium - International Astronomical Union ◽

10.1017/s0074180900084035 ◽

1998 ◽

Vol 184 ◽

pp. 65-66

Author(s):

Marc Freitag ◽

Willy Benz

Keyword(s):

Black Holes ◽

Black Hole ◽

Stellar Dynamics ◽

Stellar Cluster ◽

Stellar Collisions ◽

Galactic Black Hole ◽

Tidal Disruptions

Massive but invisible black holes (BH) are often assumed to lurk in the center of many galaxies but definitive proof of their existence has not yet been established. However, in the surrounding stellar cluster stars are unavoidably being destroyed by tidal disruptions and stellar collisions liberating of order 1M⊙ in each event. The subsequent accretion of this gas by the BH could bring it back to “life” and reveal its presence.

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