Orbital Phase Spectroscopy of four High Mass X-ray Binary Pulsars to Study the Stellar Wind of the Companion

Abstract

Our work focuses on a comprehensive orbital phase dependent spectroscopy of the four High Mass X-ray Binary Pulsars (HMXBPs) 4U 1538-52, GX 301-2, OAO 1657-415 & Vela X-1. We hereby report the measurements of the variation of the absorption column density and iron-line flux along with other spectral parameters over the binary orbit for the above-mentioned HMXBPs in elliptical orbits, as observed with the Rossi X-ray Timing Explorer (RXTE) and the BeppoSAX satellites. A spherically symmetric wind profile was used as a model to compare the observed column density variations. Out of the four pulsars, only in 4U 1538-52, we find the model having a reasonable corroboration with the observations, whereas in the remaining three the stellar wind seems to be clumpy and a smooth symmetric stellar wind model appears to be quite inadequate in explaining the data. Moreover, in GX 301-2, neither the presence of a disk nor a gas stream from the companion was validated. Furthermore, the spectral results obtained in the case of OAO 1657-415 & Vela X-1 were more or less similar to that of GX 301-2.

9 pages, 4 figures, Accepted for publication in Advances in Space Research

References in corpus (9)

• RXTE Measurement of the Diffuse X-ray Emission From the Galactic Ridge: Implications for the Energetics of the Interstellar Medium
• The mass of the neutron star in Vela X-1
• The X-Ray Spectrum and Global Structure of the Stellar Wind in Vela X-1
• VLT/UVES spectroscopy of Wray 977, the hypergiant companion to the X-ray pulsar GX301-2
• Detection of a Fully-resolved Compton Shoulder of the Iron K-alpha Line in the Chandra X-ray Spectrum of GX 301-2
• X1908+075: A Pulsar Orbiting in the Stellar Wind of a Massive Companion
• Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA
• Short term pulse frequency fluctuations of OAO 1657-415 from RXTE observations
• Vela X-1 as seen by RXTE

Cited by in corpus (4)

• Orbital Decay and Evidence of Disk Formation in the X-ray Binary Pulsar OAO 1657-415
• X-ray Spectroscopy of the High Mass X-ray Binary Pulsar Centaurus X-3 over its Binary Orbit
• Probing the stellar wind environment of Vela X-1 with MAXI
• Torque reversal and orbital profile of X-ray pulsar OAO 1657-415