Suzaku observation of Be / X-ray binary pulsar EXO 2030+375

作     者：Sachindra Naik Gaurava K.Jaisawal 

作者机构：Astronomy and Astrophysics DivisionPhysical Research Laboratory 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2015年第15卷第4期

页      面：537-548页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：the Physical Research Laboratory is funded by the Department of Space,the Government of India made use of data obtained through the HEASARC Online Service,provided by NASA/GSFC,in support of NASA High Energy Astrophysics Programs 

主　　题：pulsars: individual (EXO 2030+375)    stars: neutron    X rays: stars 

摘      要：We study the timing and spectral properties of Be/X-ray binary pulsar EXO 2030＋375 using a Suzaku observation taken on 2012 May 23, during a less intense Type I outburst. Pulsations were clearly detected in the X-ray light curves at a barycentric period of 41.2852 s, which suggest that the pulsar is spinning-up. The pulse profiles were found to be peculiar, e.g. unlike those obtained from the earlier Suzaku observation acquired on 2007 May 14. A single-peaked narrow profile at soft X-rays （0.5-10 keV range） changed to a double-peaked broad profile in the 12-55 keV energy range and again reverted back to a smooth single-peaked profile at hard X-rays （55-70 keV range）. The 1.0-100.0 keV broadband spectrum of the pulsar was found to be well described by three continuum models described as （i） a partial covering high energy cut-off power-law model, （ii） a partially absorbed power-law with high- energy exponential rolloff and （iii） a partial covering Negative and Positive power law with EXponential （NPEX） continuum model. Unlike the earlier Suzaku observation during which several low energy emission lines were detected, a weak and narrow Iron Ka emission line at 6.4 keV was only present in the pulsar spectrum during the 2012 May outburst. Non-detection of any absorption like feature in the 1-100 keV energy range supports the claim of the absence of the cyclotron resonance scattering feature in EXO 2030＋375 from the earlier Suzaku observation. Pulse-phase resolved spectroscopy revealed the presence of additional dense matter causing the absence of a second peak from the soft X-ray pulse profiles. The details of the results are described in the paper.