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Period variations in pulsating X-ray sources. I - Accretion flow parameters and neutron star structure from timing observationsTorque fluctuations which can lead to variations in the periods of pulsating X-ray sources are examined. A description of torque variations in terms of noise processes is developed, and the resulting noise models are applied to observations of several pulsating X-ray sources. It is shown that fluctuations in accretion torque could account for the observed period variations and spindown episodes in Her X-1 and Cen X-3. The values of the torque noise strengths inferred from either a nonresonant response or, in the case of Her X-1, a Tkachenko-mode interpretation of the data are found to be consistent with those expected from processes at the magnetospheric boundary of an accreting neutron star. Ways to distinguish among the various interpretations of the period variations are considered. It is noted that fluctuating mass-flow rates may be responsible for other phenomena observed in compact X-ray sources, such as wobble with zero initial amplitude and binary period variations in close binary systems experiencing mass transfer.
Document ID
19780066143
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lamb, F. K.
(Hebrew Univ. Jerusalem, Israel)
Shaham, J.
(Jerusalem, Hebrew University Jerusalem, Israel)
Pines, D.
(Hebrew Univ. Jerusalem, Israel)
Date Acquired
August 9, 2013
Publication Date
September 15, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
78A50052
Funding Number(s)
CONTRACT_GRANT: NAS5-23315
CONTRACT_GRANT: NSF AST-76-80801-A01
CONTRACT_GRANT: NSF PHY-75-08790
Distribution Limits
Public
Copyright
Other

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