Title:	Variable quasi periodic oscillations during an outburst of the transient X-ray Pulsar XTE J1858+034
Authors:	Mukherjee, U. Bapna, S. Raichur, Harsha Paul, Biswajit Jaaffrey, S.N.A.
Issue Date:	Mar-2006
Publisher:	Indian Academy of Sciences, Bangalore, India
Citation:	Journal of Astrophysics and Astronomy, 2006, Vol. 27, p25-35
Abstract:	We have investigated the Quasi Periodic Oscillation (QPO) properties of the transient accreting X-ray pulsar XTE J1858 +034 dur-ing the second outburst of this source in April-May 2004. We have used observations made with the Proportional Counter Array (PCA) of the Rossi X-ray Timing Explorer (RXTE) during May 14-18, 2004, in the declining phase of the outburst. We detected the presence of low frequency QPOs in the frequency range of 140-185 mHz in all the RXTE-PCA observations. We report evolution of the QPO parameters with the time, X-ray flux, and X-ray photon energy. Though a correlation between the QPO centroid fre-quency and the instantaneous X-ray flux is not very clear from the data, we point out that the QPO frequency and the one day averaged X-ray flux decreased with time during these observations. We have obtained a clear energy dependence of the RMS variation in the QPOs, increasing from about 3% at 3 keV to 6% at 25 keV. The X-ray pulse profile is a single peaked sinusoidal, with pulse fraction increasing from 20% at 3 keV to 45% at 30 keV. We found that, similar to the previous outburst, the energy spectrum is well fitted with a model consisting of a cut-off power law along with an iron emission line.
Description:	Open Access
URI:	http://hdl.handle.net/2289/4957
ISSN:	0250-6335
Alternative Location:	http://adsabs.harvard.edu/abs/2006JApA...27...25M http://arxiv.org/abs/astro-ph/0602559 http://dx.doi.org/10.1007/BF02702648
Copyright:	2006 Indian Academy of Sciences, Bangalore, India
Appears in Collections:	Research Papers (A&A)

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