Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA

Abstract

We have investigated the orbital phase dependence of the X-ray spectrum of the High Mass X-ray Binary pulsar GX 301--2. Here we present the results from a spectral analysis of two sets of observations of GX 301--2 with the Rossi X-ray Timing Explorer (RXTE). Of particular interest are the variations of the absorption column density and the iron line flux along with other parameters of the spectral model with the orbital phase. We found that the X-ray spectrum can almost always be fitted with a partial covering absorption model. We have detected enhanced absorption near the periastron. However, the column density variation with orbital phase is not smooth, as is expected in a smooth stellar wind model. We discuss the results of the column density variation in the light of the two proposed models for GX 301-2, an equatorial disk emanating from the companion star Wray 977 and a gas stream following the neutron star. We also found that the iron K_alpha and K_beta line fluxes have peaks near the periastron and are well correlated with the continuum hard X-ray flux. The line equivalent width shows an interesting pattern with the column density, reasonably constant for low values of the column density and increasing rapidly beyond a certain value.

arXiv comment15 pages, 7 figures. accepted in Astronomy and Astrophysics

References in corpus (1)

• Detection of a Fully-resolved Compton Shoulder of the Iron K-alpha Line in the Chandra X-ray Spectrum of GX 301-2

Cited by in corpus (23)

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• Study of the many fluorescent lines and the absorption variability in GX 301-2 with XMM-Newton
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• Suzaku observation of the transient X-ray pulsar GRO J1008-57
• Orbital phase resolved spectroscopy of GX 301-2 with MAXI
• RXTE-PCA observations of 1A 1118--61: timing and spectral studies during an outburst
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• Temporal properties of GX 301-2 over a year-long observation with SuperAGILE
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• Timing and spectral variability of high mass X-ray pulsar GX 301--2 over orbital phases observed by Insight-HXMT
• X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT
• Orbital Phase Spectroscopy of four High Mass X-ray Binary Pulsars to Study the Stellar Wind of the Companion
• Canonical X-Ray Fluorescence Line Intensities as Column Density Indicators
• Changes in the distribution of circum-binary material around the HMXB GX 301-2 during a rapid spin-up episode of the neutron star
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