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Title: Pulse phase resolved spectroscopy of Vela X-1 with Suzaku
Authors: Maitra, Chandreyee
Paul, Biswajit
Keywords: Pulsars
X-ray binaries
Issue Date: 1-Feb-2013
Publisher: IOP Sciences for The American Astronomical Society.
Citation: The Astrophysical journal, 2013, Vol.763, p79
Abstract: We present a detailed pulse-phase-resolved spectral analysis of the persistent high-mass X-ray binary pulsar Vela X-1 observed with Suzaku during 2008 June. The pulse profiles exhibit both intensity and energy dependence with multiple peaks at low energies and double peaks at higher energies. The source shows some spectral evolution over the duration of the observation and care has been taken to average over data with minimum spectral variability for the analysis. We model the continuum with a phenomenological partial covering high-energy cutoff model and a more physical partial covering thermal Comptonization model (CompTT) excluding the time ranges having variable hardness ratio and intensity dependence. For both the models, we detect a cyclotron resonant scattering feature (CRSF) and its harmonic at ~25 keV and ~50 keV. Both the CRSF fundamental and harmonics parameters are strongly variable over the pulse phase, with the ratio of the two line energies deviating from the classical value of 2. The continuum parameters also show significant variation over the pulse phase and give us some idea about the changing physical conditions that are seen with the changing viewing angle at different pulse phases and obscuration by the accretion stream at some pulse phases.
Description: Restricted Access. An open-access version is available at (one of the alternative locations). The article will be made open-access at the journal site after 24 months.
ISSN: 0004-637X
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Copyright: 2013 American Astronomical Society
Appears in Collections:Research Papers (A&A)

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