Explaining the asymmetric line profile in Cepheus X-4 with spectral variation across pulse phase
Bhargava Y, Bhalerao V, Ballhausen R, Furst F, Pottschmidt K, Tomsick JA, Wilms J (2019)
Publication Status: Published
Publication Type: Journal article
Publication year: 2019
Journal
Publisher: OXFORD UNIV PRESS
Book Volume: 482
Pages Range: 2902-2912
Journal Issue: 3
Abstract
The high mass X-ray binary Cepheus X-4, during its 2014 outburst, showed evidence for an asymmetric cyclotron line in its hard X-ray spectrum. The 2014 spectrum provides one of the clearest cases of an asymmetric line profile among all studied sources with Cyclotron Resonance Scattering Features (CRSF). We present a phase-resolved analysis of NuSTAR and Suzaku data taken at the peak and during the decline phases of this outburst. We find that the pulse-phased resolved spectra are well-fit by a single, symmetric cyclotron feature. The fit parameters vary strongly with pulse phase: most notably the central energy and depth of the cyclotron feature, the slope of the power-law component, and the absorbing column density. We synthesise a 'phase averaged' spectrum using the best-fitting parameters for these individual pulse phases, and find that this combined model spectrum has a similar asymmetry in the cyclotron features as discovered in phase-averaged data. We conclude that the pulse phase resolved analysis with simple symmetric line profiles when combined can explain the asymmetry detected in the phase-averaged data.
Authors with CRIS profile
Ralf Ballhausen
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Jörn Wilms
Professur für Astronomie und Astrophysik
Involved external institutions
University of California, Berkeley
United States (USA) (US)
University of Maryland, Baltimore County
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
Indian Institute of Technology Bombay
India (IN)
Inter-University Centre for Astronomy and Astrophysics (IUCAA)
India (IN)
United States (USA) (US)
University of Maryland, Baltimore County
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
Indian Institute of Technology Bombay
India (IN)
Inter-University Centre for Astronomy and Astrophysics (IUCAA)
India (IN)
How to cite
APA:
Bhargava, Y., Bhalerao, V., Ballhausen, R., Furst, F., Pottschmidt, K., Tomsick, J.A., & Wilms, J. (2019). Explaining the asymmetric line profile in Cepheus X-4 with spectral variation across pulse phase. Monthly Notices of the Royal Astronomical Society, 482(3), 2902-2912. https://dx.doi.org/10.1093/mnras/sty2823
MLA:
Bhargava, Yash, et al. "Explaining the asymmetric line profile in Cepheus X-4 with spectral variation across pulse phase." Monthly Notices of the Royal Astronomical Society 482.3 (2019): 2902-2912.
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