2016/11/28 by Agrawal, Vivek Kumar, Hasan, Mohammad
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.1611.09004
In this work we investigate broad band (1-79 keV) spectral nature of the atoll source 4U 1636-536 using the combined Nu-STAR and SWIFT-XRT data. The spectra are complex and have emission components from the disc, boundary-layer and corona. In addition to that a broad iron line is also observed. A relativistic line model assuming Schwarzchild metric fits this feature. The total flux varies from 1.4 × 10-9 to 4.36 × 10-9 ergs/s/cm2. At the highest flux level the source was found in the soft state. In this state the Comptonized component has temperature kTe ∼ 3 keV and optical depth τ∼ 16. We also detect a non-thermal tail with index ∼ 2.4, contributing ∼ 10 % of the total flux in the soft state. We also find that the inner disc radius, electron temperature and optical depth vary with the total 0.1-100 keV unabsorbed flux. We discuss the implication of the results in this paper.