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Short-term X-ray variability of the globular cluster source 4U 1820 - 30 (NGC 6624)Analytical techniques for improved identification of the temporal and spectral variability properties of globular cluster and galactic bulge X-ray sources are described in terms of their application to a large set of observations of the source 4U 1820 - 30 in the globular cluster NGC 6624. The autocorrelation function, cross-correlations, time skewness function, erratic periodicities, and pulse trains are examined. The results are discussed in terms of current models with particular emphasis on recent accretion disk models. It is concluded that the analyzed observations provide the first evidence for shot-noise variability in a globular cluster X-ray source.
Document ID
19840061581
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Stella, L. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA; Roma, Universita Rome, Italy)
Kahn, S. M. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Grindlay, J. E. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 12, 2013
Publication Date
July 15, 1984
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 282
ISSN: 0004-637X
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAS8-30751
Distribution Limits
Public
Copyright
Other