Two-temperature model of spherical accretion onto a black hole

Journal Article · Tue May 01 04:00:00 EDT 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161998· OSTI ID:6862397

Colpi, M; Maraschi, L; Treves, A

Spherical accretion onto a black hole is studied, considering a two-temperature plasma model. The ion and electron temperature profiles are described by two energy balance equations coupled by an energy exchange term including only Coulomb interactions between the two populations. For accretion rates smaller than the Eddington one, the proton temperature profile is closely adiabAtic. at the Schwarzschild radius the temperature approaches 10/sup 12/ K. The electron temperature at large radii is close to that of protons. Approaching the black hole, the cooling mechanisms, namely opaque synchrotron radiation and multiple Compton scattering, limit the electron temperature to approx.10/sup 9/ K. For large accretion rates (tau/sub T/roughly-equal1) the protons deviate significantly from adiabatiity, because of the energy transfer to the electrons. The temperature at the Schwarzschild radius decreases by a factor approx.2. The threshold temperature for pion production which was just reached in the very thin cases is not met for tau/sub T/roughly-equal1. The maximum achievable ..gamma..-ray flux from ..pi../sup 0/-decay is approx.2 x 10/sup 33/ ergs s/sup -1/ for a 10 M/sub sun/ hole. The electron component always contributes most (by many orders of magnitude) to the overall luminosity with an efficiency epsilon = L/Mc/sup 2/roughly-equal5 x 10/sup -3/. The spectrum is basically a power law extending from the synchrotron transparency frequency at the inner radius (10/sup 12/--10/sup 13/ Hz) to 3kT (approx.1 MeV) with spectral index varying from 1 to 0.5 for tau/sub T/ = 10/sup -2/ and tau/sub T/ = 1, respectively. All results are essentially independent of the black hole mass.

• Research Organization: Dipartimento di Fisica dell'Universita di Milano, Italy
• OSTI ID: 6862397
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 280:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
BLACK HOLES
BREMSSTRAHLUNG
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
COLLISIONS
COULOMB FIELD
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
ELECTRON COLLISIONS
ELECTRON-ION COLLISIONS
ELECTRONS
ELEMENTARY PARTICLES
EMISSION SPECTRA
ENERGY BALANCE
FERMIONS
GAMMA RADIATION
HADRON REACTIONS
HADRONS
ION COLLISIONS
IONIZING RADIATIONS
IONS
LEPTONS
MAGNETIC FIELDS
MATHEMATICAL MODELS
MESON REACTIONS
NUCLEAR REACTIONS
NUCLEONS
PION NEUTRAL REACTIONS
PION REACTIONS
PLASMA
PROTONS
RADIATIONS
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
SYNCHROTRON RADIATION