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Astron. Astrophys. 353, 617-623 (2000)

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X-ray flux and pulse frequency changes of three high mass X-ray binary pulsars: Vela X-1, GX 301-2 and OAO 1657-415

Sitki Çagdas Inam and Altan Baykal

Department of Physics, Middle East Technical University, 06531 Ankara, Turkey

Received 14 June 1999 / Accepted 7 October 1999


Using archival BATSE (Burst and Transient Source Experiment) 20-60 keV band X-ray flux and pulse frequency time series, we look for correlations between torque, luminosity and specific angular momentum for three high mass X-ray binary pulsars Vela X-1, GX 301-2 and OAO 1657-415. Our results show that there is no correlation between pulse frequency derivative and flux which may be an indication of the absence of stable prograde accretion disk. From the strong correlation of specific angular momentum and torque, we conclude that the accretion geometry changes continuously as suggested by the hydrodynamic simulations (Blondin et al. 1990).

Key words: X-rays: stars – accretion, accretion disks – stars: pulsars: individual: OAO 1657-415 – stars: pulsars: individual: GX 301-2 – stars: pulsars: individual: Vela X1

Send offprint requests to: S.Ç. Inam

© European Southern Observatory (ESO) 2000

Online publication: December 17, 1999