Black hole accretion disks: Coronal stabilization of the Lightman--Eardley instability

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

DOI:https://doi.org/10.1086/162418· OSTI ID:6249515

Ionson, J A; Kuperus, M

Black hole accretion disks are thought to play a key role in converting gravitational energy into high-energy (>1 keV) X-rays. Two categorically different theoretical models have emerged as the most likely contenders. viz., the 1977 coronal disk model of Liang and Price and the 1976 Two-temperature--disk model of Shapiro. Lightman, and Eardley. To the extent that the Lightman-Eardley (''L-E'') instability determines the appropriate models, we point out that the existence of a corona can significantly raise the instability's threshold. Specifically, coronal dissipation of accreting gravitational energy tends to decrease the ratio P/sub r//P/sub g/ within the underlying optically thick disk. This effect serves to increase the ''L-E'' instability luminosity threshold L/sub bolometric//L/sub Edd/ above the canonically accepted value by a factor of ((1+L/sub hard//L/sub soft/))/sup 9/8/, where L/sub hard/ and L/sub soft/ are the observed hard (>10 keV) and soft (<10 keV) X-ray luminosities of the source. The major result of this article is, therefore, a modified L-E instability criterion given by L/sub bolometric//L/sub Edd/>7.7 x 10/sup -3/(..cap alpha..M/M/sub sun/)/sup -1/8/(1 +(L/sub hard//L/sub soft/))/sup 9/8/, where L/sub hard//L/sub soft/ is an observable measure of the coronal heating efficiency.

• Research Organization: Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center
• OSTI ID: 6249515
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 284:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics &amp; Cosmology-- Stars &amp; Quasi-Stellar
Radio &amp; X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
ATMOSPHERES
BLACK HOLES
ELECTROMAGNETIC RADIATION
GRAVITATION
HEATING
INSTABILITY
IONIZING RADIATIONS
LUMINOSITY
MATHEMATICAL MODELS
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STELLAR ATMOSPHERES
X RADIATION