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Critical radiation fluxes and luminosities of black holes and relativistic starsThe critial luminosity at which the outward force of radiation balances the inward force of gravity plays an important role in many astrophysical systems. We present expressions for the radiation force on particles with arbitrary cross sections and analyze the radiation field produced by radiating matter, such as a disk, ring, boundary layer, or stellar surface, that rotates slowly around a slowly rotating gravitating mass. We then use these results to investigate the critical radiation flux and, where possible, the critical luminosity of such a system in genral relativity. We demonstrate that if the radiation source is axisymmetric and emission is back-front symmetric with repect to the local direction of motion of the radiating matter, as seen in the comoving frame, then the radial component of the radiation flux and the diagonal components of the radiation stress-energy tensor outside the source are the same, to first order in the rotation rates, as they would be if the radiation source and gravitating mass were not rotating. We argue that the critical radiation flux for matter at rest in the locally nonrotating frame is often satisfactory as an astrophysical benchmark flux and show that if this benchmark is adopted, many of the complications potentially introduced by rotation of the radiation source and the gravitating mass are avoided. We show that if the radiation field in the absence of rotation would be spherically symmetric and the opacity is independent of frequency and direction, one can define a critical luminosity for the system that is independent of frequency and direction, one can define a critical luminosity for the system that is independent of the spectrum and angular size of the radiation source and is unaffected by rotation of the source and mass and orbital motion of the matter, to first order. Finally, we analyze the conditions under which the maximum possible luminosity of a star or black hole powered by steady spherically symmetric radial accretion is the same in general relativity as in the Newtonian limit.
Document ID
19950044721
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lamb, Frederick K.
(Univ. of Illinois at Urbana-Champaign, Urbana, IL United States)
Miller, M. Coleman
(Univ. of Illinois at Urbana-Champaign, Urbana, IL United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1995
Publication Information
Publication: The Astrophysical Journal, Part 1
Volume: 439
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A76320
Funding Number(s)
CONTRACT_GRANT: NAGW-830
CONTRACT_GRANT: NAGW-1583
CONTRACT_GRANT: NSF PHY-91-00283
CONTRACT_GRANT: NAG5-28543
CONTRACT_GRANT: NSF AST-93-15133
Distribution Limits
Public
Copyright
Other

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