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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/4929

Title: Changes in the long-term intensity variations in cygnus X-2 and LMC X-3
Authors: Paul, Biswajit
Kitamoto, S.
Makino, F.
Keywords: accretion disks
stars: neutron
X-Rays: Stars
Issue Date: Jan-2000
Publisher: IOP Publishing Ltd.
Citation: Astrophysical Journal, 2000, Vol. 528, p410-417
Abstract: We report the detection of changes in the long-term intensity variations in two X-ray binaries, Cyg X-2 and LMC X-3. In this work, we have used the long-term light curves obtained with the All-Sky Monitors (ASMs) of the Rossi X-Ray Timing Explorer (RXTE), Ginga, Ariel 5, and Vela 5B and the scanning modulation collimator of HEAO 1. It is found that in the light curves of both the sources, obtained with these instruments at various times over the last 30 years, more than one periodic or quasi-periodic component is always present. The multiple prominent peaks in the periodograms have frequencies unrelated to each other. In Cyg X-2, RXTE-ASM data show strong peaks at 40.4 and 68.8 days, and Ginga-ASM data show strong peaks at 53.7 and 61.3 days. Multiple peaks are also observed in LMC X-3. The various strong peaks in the periodograms of LMC X-3 appear at 104, 169, and 216 days (observed with RXTE-ASM) and 105, 214, and 328 days (observed with Ginga-ASM). The present results, when compared with the earlier observations of periodicities in these two systems, demonstrate the absence of any stable long period. The 78 day periodicity detected earlier in Cyg X-2 was probably due to the short time base in the RXTE data that were used, and the periodicity of 198 days in LMC X-3 was due to a relatively short duration of observation with HEAO 1.
Description: Open Access
URI: http://hdl.handle.net/2289/4929
ISSN: 0004-637X
1538-4357 (Online)
Alternative Location: http://adsabs.harvard.edu/abs/2000ApJ...528..410P
http://arxiv.org/abs/astro-ph/0002219
http://dx.doi.org/10.1086/308149
Copyright: 2000 The American Astronomical Society
Appears in Collections:Research Papers (A&A)

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