Abstract Details
| Name: Gaurava K Jaisawal Affiliation: Physical Research Laboratory, Ahmedabad Conference ID: ASI2016_432 Title : Suzaku observations of the Be/X-ray binary pulsar GX 304-1 Authors and Co-Authors : Sachindra Naik (PRL, Ahmedabad) and Prahlad Epili (PRL, Ahmedabad) Abstract Type : Oral Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : We studied the broad-band spectral and timing properties of Be/X-ray binary pulsar GX 304-1, using two Suzaku observations during its outbursts in 2010 and 2012. X-ray pulsations were detected at ~275 s during both observations. Pulse profiles of the pulsar were strongly energy dependent. Soft X-ray pulse profile was found to be multi-peaked (with absorption dips) which evolved into a single peaked profile at higher energies. Significant changes in pulse profiles were detected in hard X-rays. The pulse profiles above 35 keV show a sudden change in profile pattern with shifted (~0.3 pulse-phase) main dip. The broadband energy spectrum of the pulsar was well described with partial absorbed Negative and Positive Exponential cutoff (NPEX) continuum model with 6.4 keV iron emission line and a cyclotron absorption feature. The cyclotron absorption line was detected at ~53 and 50 keV during 2010 and 2012 Suzaku observations, respectively. We have found a marginal positive dependence between cyclotron line energy and luminosity during Suzaku observations. The phase-resolved spectroscopy was performed to study the changes in spectral parameters around the pulsar. It was found that the presence of additional matter at certain pulse phases of the pulsar cause the absorption dips or multi-peak structures in soft X-ray pulse profiles. The cyclotron energy and depth were significantly variable (<24 %) with pulsar-phases. The observed variation in the cyclotron line parameters during both observations can be explained as due to the effect of the viewing angle or role of the complicated magnetic field of the pulsar. |