Suzaku Observation of Be/X-ray Binary Pulsar EXO 2030+375

Abstract

In this paper we study the timing and spectral properties of Be/X-ray binary pulsar EXO 2030+375 using a $Suzaku$ observation 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 suggests that the pulsar is spinning-up. The pulse profiles were found to be peculiar e.g. unlike that obtained from the earlier Suzaku observation 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 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 broad-band spectrum of the pulsar was found to be well described by three continuum models such 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 earlier Suzaku observation during which several low energy emission lines were detected, a weak and narrow Iron K_alpha 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 1-100 keV energy range supports the claim of absence of cyclotron resonance scattering feature in EXO 2030+375 from earlier Suzaku observation. Pulse-phase resolved spectroscopy revealed the presence of additional dense matter causing the absence of second peak from the soft X-ray pulse profiles. The details of the results are described in the paper.

12 pages, 7 figures

References in corpus (5)

• Outbursts Large and Small from EXO 2030+375
• Giant outburst of EXO 2030+375: pulse-phase resolved analysis of INTEGRAL data
• Timing and Spectral properties of Be/X-ray pulsar EXO 2030+375 during a Type I outburst
• Suzaku observation of the transient X-ray pulsar GRO J1008-57
• Broad band X-ray spectroscopy of A0535+262 with SUZAKU

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• Spectral & Timing analysis of Be/X-ray binary EXO 2030+375 during its giant 2021 outburst
• AstroSat observation of the Be/X-ray binary Pulsar 3A 0726-260 (4U 0728-25)