Cosmic Distributions of Stellar Tidal Disruptions by Massive Black Holes at Galactic Centers

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.

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Gaseous Disks in the Nuclei of Elliptical Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100043293 ◽

1997 ◽

Vol 163 ◽

pp. 620-625 ◽

Cited By ~ 4

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.

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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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