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http://hdl.handle.net/2289/6009| Title: | Variations in the pulsation and spectral characteristics of OAO 1657-415 |
| Authors: | Pradhan, Pragati Maitra, Chandreyee Paul, Biswajit Islam, Nazma Paul, B.C. |
| Keywords: | Pulsars X-ray binaries |
| Issue Date: | 11-Aug-2014 |
| Publisher: | Oxford University Press for The Royal Astronomical Society |
| Citation: | Monthly Notices of the Royal Astronomical Society, 2014, Vol. 443, p2691-2700 |
| Abstract: | We present broad-band pulsation and spectral characteristics of the accreting X-ray pulsar OAO 1657−415 with a 2.2 d long Suzaku observation carried out covering its orbital phase range ∼0.12–0.34, with respect to the mid-eclipse. During the last third of the observation, the X-ray count rate in both the X-ray Imaging Spectrometer (XIS) and the HXD-PIN instruments increased by a factor of more than 10. During this observation, the hardness ratio also changed by a factor of more than 5, uncorrelated with the intensity variations. In two segments of the observation, lasting for ∼30–50 ks, the hardness ratio is very high. In these segments, the spectrum shows a large absorption column density and correspondingly large equivalent widths of the iron fluorescence lines. We found no conclusive evidence for the presence of a cyclotron line in the broad-band X-ray spectrum with Suzaku. The pulse profile, especially in the XIS energy band, shows evolution with time but not so with energy. We discuss the nature of the intensity variations, and variations of the absorption column density and emission lines during the duration of the observation as would be expected due to a clumpy stellar wind of the supergiant companion star. These results indicate that OAO 1657−415 has characteristics intermediate to the normal supergiant systems and the systems that show fast X-ray transient phenomena. |
| Description: | Open Access. |
| URI: | http://hdl.handle.net/2289/6009 |
| ISSN: | 0035-8711 1365-2966 - (online) |
| Alternative Location: | http://adsabs.harvard.edu/abs/2014MNRAS.442.2691P http://arxiv.org/abs/1407.5252 http://dx.doi.org/10.1093/mnras/stu1034 |
| Copyright: | 2014 The authors & the Royal Astronomical Society |
| Appears in Collections: | Research Papers (A&A) |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 2014_MNRAS_442_2691.pdf | Open Access | 1.06 MB | Adobe PDF | View/Open |
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