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Detection of Cyclotron Resonance Scattering Feature in High Mass X-ray Binary Pulsar SMC X-2

Jaisawal, Gaurava K. and Naik, Sachindra (2016) Detection of Cyclotron Resonance Scattering Feature in High Mass X-ray Binary Pulsar SMC X-2. Monthly Notices of the Royal Astronomical Society: Letters, 461 (1). L97-L101. ISSN 1745-3925. doi:10.1093/mnrasl/slw108.

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We report broad-band spectral properties of the high-mass X-ray binary pulsar SMC X-2 by using three simultaneous Nuclear Spectroscopy Telescope Array and Swift/XRT observations during its 2015 outburst. The pulsar was significantly bright, reaching a luminosity up to as high as ∼5.5 × 10^(38) erg s^(−1) in 1–70 keV range. Spin period of the pulsar was estimated to be 2.37 s. Pulse profiles were found to be strongly luminosity dependent. The 1–70 keV energy spectrum of the pulsar was well described with three different continuum models such as (i) negative and positive power law with exponential cutoff, (ii) Fermi-Dirac cutoff power law and (iii) cutoff power-law models. Apart from the presence of an iron line at ∼6.4 keV, a model independent absorption like feature at ∼27 keV was detected in the pulsar spectrum. This feature was identified as a cyclotron absorption line and detected for the first time in this pulsar. Corresponding magnetic field of the neutron star was estimated to be ∼2.3 × 10^(12) G. The cyclotron line energy showed a marginal negative dependence on the luminosity. The cyclotron line parameters were found to be variable with pulse phase and interpreted as due to the effect of emission geometry or complicated structure of the pulsar magnetic field.

Item Type:Article
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URLURL TypeDescription Paper
Jaisawal, Gaurava K.0000-0002-6789-2723
Naik, Sachindra0000-0003-2865-4666
Additional Information:© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 May 23. Received 2016 May 23; in original form 2016 May 4. Published: 25 May 2016. We sincerely thank the referee for his/her valuable comments and suggestions which improved the Letter. The research work at Physical Research Laboratory is funded by the Department of Space, Government of India. The authors would like to thank all the NuSTAR and Swift team members for ToO observations. This research has made use of data from HEASARC Online Service, and the NuSTAR Data Analysis Software (NUSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA).
Subject Keywords:stars: neutron – pulsars: individual: SMC X-2 – X-rays: stars
Issue or Number:1
Record Number:CaltechAUTHORS:20170520-161330425
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Official Citation:Gaurava K. Jaisawal, Sachindra Naik; Detection of cyclotron resonance scattering feature in high-mass X-ray binary pulsar SMC X-2, Monthly Notices of the Royal Astronomical Society: Letters, Volume 461, Issue 1, 1 September 2016, Pages L97–L101,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77611
Deposited By: Joy Painter
Deposited On:21 May 2017 19:03
Last Modified:15 Nov 2021 17:32

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