Two temperature viscous accretion flows around rotating black holes: Description of under-fed systems to ultra-luminous X-ray sources

Rajesh, SR and Mukhopadhyay, Banibrata (2010) Two temperature viscous accretion flows around rotating black holes: Description of under-fed systems to ultra-luminous X-ray sources. In: New Astronomy, 15 (3). pp. 283-291.

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Abstract

We discuss two temperature accretion disk flows around rotating black holes. As we know that to explain observed hard X-rays the choice of Keplerian angular momentum profile is not unique, we consider the sub-Keplerian regime of the disk. Without any strict knowledge of the magnetic field structure, we assume the cooling mechanism is dominated by bremsstrahlung process. We show that in a range of Shakura-Sunyaev viscosity parameter 0.2 greater than or similar to alpha greater than or similar to 0.0005, flow behavior varies widely, particularly by means of the size of disk, efficiency of cooling and corresponding temperatures of ions and electrons. We also show that the disk around a rotating black hole is hotter compared to that around a Schwarzschild black hole, rendering a larger difference between ion and electron temperatures in the former case. With all the theoretical solutions in hand, finally we reproduce the observed luminosities (L) of two extreme cases-the under-fed AGNs and quasars (e.g. Sgr A') with L greater than or similar to 10(33) erg/s to ultra-luminous X-ray sources with L similar to 10(41) erg/s, at different combinations of mass accretion rate, ratio of specific heats, Shakura-Sunyaev viscosity parameter and Kerr parameter, and conclude that Sgr A' may be an intermediate spinning black hole.

Item Type:	Journal Article
Publication:	New Astronomy
Publisher:	Elsevier Science
Additional Information:	Copyright for this article belongs to Elsevier Science.
Keywords:	Accretion, accretion disk; Black hole physics; Hydrodynamics; Radiative transfer; Gravitation
Department/Centre:	Division of Physical & Mathematical Sciences > Astronomy and Astrophysics Programme
Date Deposited:	12 Jan 2010 08:46
Last Modified:	19 Sep 2010 05:54
URI:	http://eprints.iisc.ac.in/id/eprint/25358

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