Two temperature viscous accretion flows around rotating black holes: Description of under-fed systems to ultra-luminous X-ray sources
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≳α≳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≳1033erg/s to ultra-luminous X-ray sources with L∼1041 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.
- Publication:
-
New Astronomy
- Pub Date:
- March 2010
- DOI:
- 10.1016/j.newast.2009.08.005
- arXiv:
- arXiv:0908.3956
- Bibcode:
- 2010NewA...15..283R
- Keywords:
-
- 97.10.Gz;
- 97.60.Lf;
- 95.30.Lz;
- 95.30.Jx;
- 04.70.s;
- Accretion and accretion disks;
- Black holes;
- Hydrodynamics;
- Radiative transfer;
- scattering;
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology
- E-Print:
- 21 pages including 5 figures