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 and 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 and Vela X-1 were more or less similar to that of GX 301-2.
- Publication:
-
Advances in Space Research
- Pub Date:
- March 2009
- DOI:
- 10.1016/j.asr.2008.12.011
- arXiv:
- arXiv:0812.4519
- Bibcode:
- 2009AdSpR..43..900N
- Keywords:
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- Astrophysics
- E-Print:
- 9 pages, 4 figures, Accepted for publication in Advances in Space Research