Year: 1997
Type: article
Abstract: We present analytical scaling laws for self-similar advection-dominated flows. The spectra from these systems range from 10 8 to 10 20 Hz and are determined by considering cooling of electrons through synchrotron, bremsstrahlung, and Compton processes. We show that the spectra can be quite accurately reproduced without detailed numerical calculations and that there is a strong testable correlation between the radio and X-ray fluxes from these systems. We describe how different regions of the spectrum scale with the mass of the accreting black hole, M , the accretion rate of the gas, , and the equilibrium temperature of the electrons, T e . We show that the universal radio spectral index of 1/3 observed in most elliptical galaxies (Slee et al.) is a natural consequence of self-absorbed synchrotron radiation from these flows. We also give expressions for the total luminosity of these flows and the critical accretion rate, crit , above which the advection solutions cease to exist. We find that for most cases of interest, the equilibrium electron temperature is fairly insensitive to M , , and parameters in the model. We apply these results to low-luminosity black holes in galactic nuclei. We show that the problem posed by Fabian & Canizares of whether bright elliptical galaxies host dead quasars is resolved, as pointed out recently by Fabian & Rees, by considering advection-dominated flows.
Source: The Astrophysical Journal
DOI: 10.1086/303727
Author: Rohan Mahadevan
Institution: Center for Astrophysics Harvard & Smithsonian
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: National Science Foundation
OpenAlex ID: W2042190859