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Low-frequency quasi-periodic oscillations in low-mass X-ray binaries and galactic black hole candidatesWe consider the inner regions of accretion disks surrounding black holes and neutron stars and investigate the nonlinear time-dependent evolution of thermal-viscous instabilities. The viscous stress is assumed to be proportional to the gas pressure with the viscosity parameter formulated as alpha = min alpha (sub zero) (h/r) (exp n), alpha(sub max), where h is the local scale height, r is the distance from the central compact object, and n, alpha(sub zero) and alpha(sub max) are constants. It is found that the disk is unstable for alpha sufficiently sensitive to h (n greater than or equal to 1.2). The instabilities are globally coherent in the entire unstable region of the disk, and, depeding on the viscosity parameters, the time variability of the mass accretion rates are manifested as periodic or quasi-periodic oscillations. We show that, the low-frequency (approximately 0.04 Hz) quasi-periodic oscillations (QPOs) discovered recently in some of the black hole candidates (Cyg X-1 and GRO J0422+32) and a low-mass X-ray binary (Rapid Burster MXB 1730-335) may be explicable by the thermal-viscous instabilities in accretion disks. The observations of QPOs place constraints on the viscosity parameters and suggest that (n, alpha(sub zero) approximately (1.6, 30) for the Rapid Burster with a 1.4 solar mass neutron star. In the case of black hole candidates, the dependence of alpha on h/r is less steep corresponding to n approximately 1.2-1.3 for black holes less than 10 solar mass.
Document ID
19950029375
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Chen, Xingming
(Northwestern Univ. Evanston, IL, United States)
Taam, Ronald E.
(Northwestern Univ. Evanston, IL, United States)
Date Acquired
August 16, 2013
Publication Date
August 20, 1994
Publication Information
Publication: The Astrophysical Journal
Volume: 431
Issue: 2 pt
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A60974
Funding Number(s)
CONTRACT_GRANT: NAGW-2526
Distribution Limits
Public
Copyright
Other

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