INTEGRAL observations of the variability of OAO 1657-415

Abstract

The Galactic Plane Scan (GPS) was one of the core observation programmes of the INTEGRAL satellite. The highly variable accreting pulsar OAO 1657-415 was frequently observed within the GPS. We investigate the spectral and timing properties of OAO 1657-415 and their variability on short and long time scales in the energy range 6-160 keV. During the time covered by the INTEGRAL observations, the pulse period evolution shows an initial spin-down, which is followed by an equally strong spin-up. In combining our results with historical pulse period measurements (correcting them for orbital variation) and with stretches of continuous observations by BATSE, we find that the long-term period evolution is characterised by a long-term spin-up overlayed by sets of relative spin-down/spin-up episodes, which appear to repeat quasi-periodically on a 4.8 yr time scale. We measure an updated local ephemeris and confirm the previously determined orbital period with an improved accuracy. The spectra clearly change with pulse phase. The spectrum measured during the main peak of the pulse profile is particularly hard. We do not find any evidence of a cyclotron line, wether in the phase-averaged spectrum or in phase-resolved spectra.

arXiv comment12 pages, 11 figures

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Cited by in corpus (25)

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• Timing Characteristics of the Hard X-ray Emission from Bright X-ray Pulsars Based on INTEGRAL Data
• Orbital Decay and Evidence of Disk Formation in the X-ray Binary Pulsar OAO 1657-415
• Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in Supergiant Fast X-ray Transient and classical Supergiant X-ray Binaries
• The evolution and masses of the neutron star and donor star in the high mass X-ray binary OAO 1657-415
• Spectral classification of the mass donors in the high-mass X-ray binaries EXO 1722-363 and OAO 1657-415
• Variations in the pulsation and spectral characteristics of OAO 1657-415
• INTEGRAL 11-year hard X-ray survey above 100 keV
• XMM-Newton spectroscopy of the accreting magnetar candidate 4U0114+65
• Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122
• Catalog of the Galactic population of X-ray pulsars in High-mass X-ray binary systems
• Properties and observability of glitches and anti-glitches in accreting pulsars
• Soft gamma-ray sources detected by INTEGRAL
• Timing and Spectral Analysis of HMXB OAO 1657-415 with NuSTAR
• Multitude of iron lines including a Compton scattered component in OAO 1657--415 detected with Chandra
• A NuSTAR observation of the eclipsing binary system OAO 1657-415: The revival of the cyclotron line
• X-ray pulsars through the eyes of INTEGRAL
• Torque reversal and orbital profile of X-ray pulsar OAO 1657-415
• Discovery of twin kHz quasi periodic oscillations in the low mass X-ray binary XTE J1701-407
• Timing and spectral studies of Cen X-3 in multiple luminosity states using $\text{AstroSat}$
• AstroSat observations of eclipsing high mass X-ray binary pulsar OAO 1657-415
• Variability study of the High Mass X-ray Binary IGR J18027--2016 with {\it Swift}--XRT
• Clumpy wind studies and the non-detection of cyclotron line in OAO 1657-415
• On the origin of super-global spin-up trends of X-ray pulsars in HMXB systems