Title:	Suzaku observation of the eclipsing high mass X-ray binary pulsar XTE J1855-026.
Authors:	Devasia, Jincy Paul, Biswajit
Keywords:	X-ray neutron stars XTE J1855-026
Issue Date:	Feb-2018
Publisher:	Springer for Indian Academy of Sciences
Citation:	Journal of Astrophysics and Astronomy, 2018, Vol.39, p7
Abstract:	We report results from analysis performed on an eclipsing supergiant high mass X-ray binary pulsar XTE J1855-026 observed with the X-ray Imaging Spectrometer (XIS) on-board Suzaku Observatory in April 2015. Suzaku observed this source for a total effective exposure of ∼87 ks just before an eclipse. Pulsations are clearly observed and the pulse profiles of XTE J1855-026 did not show significant energy dependence during this observation consistent with previous reports. The time averaged energy spectrum of XTE J1855-026 in the 1.0–10.5 keV energy range can be well fitted with a partial covering power law model modified with interstellar absorption along with a black-body component for soft excess and a gaussian for iron fluorescence line emision. The hardness ratio evolution during this observation indicated significant absorption of soft X-rays in some segments of the observation. For better understanding of the reason behind this, we performed time-resolved spectroscopy in the 2.5–10.5 keV energy band which revealed significant variations in the spectral parameters, especially the hydrogen column density and iron line equivalent width with flux. The correlated variations in the spectral parameters indicate towards the presence of clumps in the stellar wind of the companion star accounting for the absorption of low energy X-rays in some time segments.
Description:	Open Access
URI:	http://hdl.handle.net/2289/6916
ISSN:	0250-6335 0973-7758 (Online)
Alternative Location:	http://adsabs.harvard.edu/abs/2018JApA...39....7D https://link.springer.com/article/10.1007/s12036-017-9496-z
Copyright:	2018 Indian Academy of Sciences
Appears in Collections:	Research Papers (A&A)

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