The dynamics of dissipatively heated spherical accretion
Abstract
The dynamical equations that describe dissipatively heated spherical accretion onto a black hole are developed, without the customary assumption of equipartition between the magnetic energy density and the gravitational potential energy density. Instead, the (somewhat arbitrary) assumption is made that, after averaging over a spherical surface, the local electric field associated with the magnetic field dissipation is a fixed fraction of the Alfven velocity times the radial field strength. A dynamically significant radial stress term appears in the momentum equation; the stress is shown also to be required by energy conservation, irrespective of the electric field assumption. The radial stress gives rise to an instability of the flow, characterized by density and temperature fluctuations of opposite sign. The instability has implications for the variability and Comptonization of the luminosity of quasars and active galactic nuclei.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1983
- DOI:
- 10.1086/161291
- Bibcode:
- 1983ApJ...272..279S
- Keywords:
-
- Black Holes (Astronomy);
- Energy Dissipation;
- Galactic Nuclei;
- Quasars;
- Stellar Mass Accretion;
- Active Galactic Nuclei;
- Dynamic Models;
- Flow Stability;
- Magnetohydrodynamic Flow;
- Astrophysics