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Orbital Evolution and Orbital Phase Resolved Spectroscopy of the HMXB Pulsar 4U 1538–52 with RXTE-PCA and BeppoSAX

Mukherjee, U and Raichur, H and Paul, B and Naik, S and Bhatt, N (2006) Orbital Evolution and Orbital Phase Resolved Spectroscopy of the HMXB Pulsar 4U 1538–52 with RXTE-PCA and BeppoSAX. In: Journal of Astrophysics and Astronomy, 27 (4). pp. 411-423.


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We report here results from detailed timing and spectral studies of the high mass X-ray binary pulsar 4U 1538–52 over several binary periods using observations made with the Rossi X-rayTiming Explorer (RXTE) and BeppoSAX satellites. Pulse timing analysis with the 2003 RXTE data over two binary orbits confirms an eccentric orbit of the system. Combining the orbitial parameters determined from this observation with the earlier measurements we did not find any evidence of orbital decay in this X-ray binary. We have carried out orbital phase resolved spectroscopy to measure changes in the spectral parameters with orbital phase, particularly the absorption column density and the iron line flux. The RXTE-PCA spectra in the 3–20 keV energy range were fitted with a power law and a high energy cut-off alongwith a Gaussian line at $\sim 6.4 keV$, whereas the BeppoSAX spectra needed only a power law and Gaussian emission line at $\sim 6.4 keV$ in the restricted energy range of 0.3–10.0 keV. An absorption along the line of sight was included for both the RXTE and BeppoSAX data. The variation of the free spectral parameters over the binary orbit was investigated and we found that the variation of the column density of absorbing material in the line of sight with orbital phase is in reasonable agreement with a simple model of a spherically symmetric stellar wind from the companion star.

Item Type: Journal Article
Publication: Journal of Astrophysics and Astronomy
Publisher: Indian Academy of Sciences
Additional Information: Copyright of this article belongs to Indian Academy of Sciences.
Keywords: Stars;Binaries;Eclipsing—stars;Pulsars;Individual;4U 1538–52—X-rays;Stars
Department/Centre: Division of Physical & Mathematical Sciences > Joint Astronomy Programme
Date Deposited: 20 Aug 2007
Last Modified: 19 Sep 2010 04:39
URI: http://eprints.iisc.ac.in/id/eprint/11716

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