Selfconsistent Models of Spherical Accretion onto Black Holes. I. OneTemperature Solutions
Abstract
Spherically symmetric, steady state accretion onto a black hole is considered for various dimensionless accretion rates m^dot^ (=M^dot^c^2^/L_E_, where M^dot^ is the accretion rate and L_E_ is the Eddington luminosity). Models are constructed by iteratively integrating relativistic hydrodynamic and radiation moment equations with bremsstrahlung and Comptonization as the main radiative processes. Electrons and ions are assumed to be coupled completely. The effects of preheating, and the shock that may result, are also considered. At least one type of selfconsistent model is found for any m^dot^, self consistency meaning that the gas at all radii is heated by the radiation it produces. Two sets of models (characterized by different temperatures) were found in the range 3 <~ m^dot^ <~ 100. The dimensionless luminosity l (=L/L_E_) is 5.8 x 10^5^m^dot^^2^ for m^dot^ < I. Lowtemperature models (T ~ 10^4^ K), which exist for m^dot^ >~ 0.1, have l ~ 7 x 10^10^m^dot^ln(10^8^/m^dot^); hightemperature models, which exist for 3 <~ m^dot^ <~ 100, have 3 x 10^4^ <~ l <~ 3 x 10^2^. The m^dot^ = 100 model has the highest luminosity of all: l = 2.6 x 10^2^. Highm^dot^ models have correct mean photon energies for AGNs. Because of the effects of preheating, no steady state hightemperature selfconsistent solution exists for 0.1 <~ m^dot^<~ 3 without a shock, and none exists for m^dot^ >~ 100 regardless of the presence or absence of a shock. The calculations also suggest that the hightemperature m^dot^ > 1 model is unstable at a fixed accretion rate.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 1990
 DOI:
 10.1086/168668
 Bibcode:
 1990ApJ...354...64P
 Keywords:

 Accretion Disks;
 Astronomical Models;
 Black Holes (Astronomy);
 Computational Astrophysics;
 Quasars;
 Temperature Effects;
 Active Galactic Nuclei;
 Coulomb Collisions;
 Emission Spectra;
 Iterative Solution;
 Luminosity;
 Pair Production;
 Radiative Transfer;
 Stellar Mass Accretion;
 black holes;
 hydrodynamics;
 radiation mechanisms;
 quasars;
 Astrophysics;
 BLACK HOLES;
 HYDRODYNAMICS;
 RADIATION MECHANISMS;
 QUASARS