TY - JOUR

T1 - A recipe for making hot accretion disks

AU - Björnsson, Gunnlaugur

AU - Svensson, Roland

PY - 1991/4/20

Y1 - 1991/4/20

N2 - A powerful new method to determine the structure of effectively optically thin accretion disks (even when complicated microphysics is included) has been discovered. The method reduces the set of equations that needs to be solved numerically to the microphysical equations only. Furthermore, the method reduces the dimension of the parameter space that needs to be explored from three (accretion rate, viscosity, radius) to two ("proton optical depth," τp, and compactness, l) significantly reducing the computational effort. The method contains two steps. First, the equilibrium states of hot plasma clouds (HPCs) are determined as a function of τp and l by solving the microphysical equations. Then the disk structure equations are solved analytically giving two relations between the HPC parameters, τp and l, and two accretion disk parameters. The two relations map the computed equilibrium states into the accretion disk parameter space. The disk structure for τp or l for all applicable accretion rates, viscosities, and radii can conveniently be visualized in one single figure. As a tutorial example, disk structures are constructed for effectively optically thin brems-strahlung disks.

AB - A powerful new method to determine the structure of effectively optically thin accretion disks (even when complicated microphysics is included) has been discovered. The method reduces the set of equations that needs to be solved numerically to the microphysical equations only. Furthermore, the method reduces the dimension of the parameter space that needs to be explored from three (accretion rate, viscosity, radius) to two ("proton optical depth," τp, and compactness, l) significantly reducing the computational effort. The method contains two steps. First, the equilibrium states of hot plasma clouds (HPCs) are determined as a function of τp and l by solving the microphysical equations. Then the disk structure equations are solved analytically giving two relations between the HPC parameters, τp and l, and two accretion disk parameters. The two relations map the computed equilibrium states into the accretion disk parameter space. The disk structure for τp or l for all applicable accretion rates, viscosities, and radii can conveniently be visualized in one single figure. As a tutorial example, disk structures are constructed for effectively optically thin brems-strahlung disks.

KW - Accretion

KW - Black holes

KW - X-rays: general

KW - X-rays: sources

UR - http://www.scopus.com/inward/record.url?scp=4243575480&partnerID=8YFLogxK

U2 - 10.1086/186004

DO - 10.1086/186004

M3 - Article

AN - SCOPUS:4243575480

VL - 371

SP - L69-L72

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 PART 2

ER -