Quasi-Periodic Oscillations in Cen X-3 and the Long-Term Intensity Variations

Raichur, Harsha and Paul, Biswajit (2008) Quasi-Periodic Oscillations in Cen X-3 and the Long-Term Intensity Variations. In: The Astrophysical Journal, 685 (2). pp. 1109-1113.

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Abstract

We have investigated the properties of the quasi-periodic oscillation (QPO) features in the accretion-powered X-ray pulsar Cen X-3 over a period of about 4 years using observations carried out with the Proportional Counter Array (PCA) of the Rossi X-ray Timing Explorer (RXTE). The observations cover a wide range of X-ray intensity of the source in excess of the binary intensity modulation. In 11 of 81 pointings with the PCA, we have detected QPOs with rms intensity fluctuation up to 10%. The QPO peak frequency shows clustering around 40 and 90 mHz, with the QPO frequency having no dependence on X-ray intensity. This indicates that either (1) the observed X-ray luminosity of the source is not related to the mass accretion rate or inner radius of the accretion disk, or (2) the QPO generation mechanism in Cen X-3 is different from the beat frequency model or Keplerian frequency model that is believed to operate in most other transient and persistent X-ray pulsars. We have also found that the rms variation in the 40 mHz QPO feature is not dependent on the X-ray energy, indicating that the origin of the QPO is unlikely to be related to disk absorption.

Item Type:	Journal Article
Publication:	The Astrophysical Journal
Publisher:	University of Chicago Press
Additional Information:	Copyright of this article belongs to University of Chicago Press
Department/Centre:	Division of Physical & Mathematical Sciences > Joint Astronomy Programme
Date Deposited:	14 May 2009 07:25
Last Modified:	19 Sep 2010 04:54
URI:	http://eprints.iisc.ac.in/id/eprint/16854

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