Short term pulse frequency fluctuations of OAO 1657-415 from RXTE observations

Abstract

We present new X-ray observations of the high mass X-ray binary (HMXRB) pulsar OAO 1657-415, obtained during one orbital period (10.44 days) with the Rossi X-Ray Timing Explorer (RXTE). Using the binary orbital parameters, obtained from Burst and Transient Source Experiment (BATSE) observations, we resolve the fluctuations in the pulse frequency at time scales on the order of one day for the first time. Recent BATSE results showed that OAO 1657-415 has spin-up/down trends in its pulse frequency time series, without any correlation with the X-luminosity at energies $>$20 keV (Baykal 1997). In the present RXTE observations the source is found to be in an extended phase of spin-down. We also find a gradual increase in the X-ray luminosity which is correlated with a marginal spin-up episode. The marginal correlation between the gradual spin-up (or decrease in spin-down rate) and increase in X-ray luminosity suggests that the OAO 1657-415 is observed during a stable accretion episode where the prograde accretion disk is formed.

MNRAS (2000), vol 313, 637

References in corpus (3)

• Observations of Accreting Pulsars
• In-flight Performance of the High Energy X-ray Timing Experiment on the Rossi X-ray Timing Explorer
• On the Dramatic Spin-up/Spin-down Torque Reversals in Accreting Pulsars

Cited by in corpus (13)

• Hard Spectra of X-Ray Pulsars from INTEGRAL Data
• Long-term Properties of Accretion Disks in X-ray Binaries: II. Stability of Radiation-Driven Warping
• INTEGRAL observations of the variability of OAO 1657-415
• The X-Ray Position and Infrared Counterpart of the Eclipsing X-Ray Pulsar OAO 1657-415
• ASCA Observations of OAO 1657-415 and its Dust-Scattered X-Ray Halo
• Variations in the pulsation and spectral characteristics of OAO 1657-415
• Spin evolution of long-period X-ray pulsars
• Timing and Spectral Analysis of HMXB OAO 1657-415 with NuSTAR
• Viscous timescale in high mass X-ray binaries
• Comprehensive Timing and X-ray Spectral Analysis of GX 1+4
• Pulse Frequency Fluctuations of Persistent Accretion Powered Pulsars
• Orbital Phase Spectroscopy of four High Mass X-ray Binary Pulsars to Study the Stellar Wind of the Companion
• AstroSat observations of eclipsing high mass X-ray binary pulsar OAO 1657-415