Study of reprocessing of X‐rays in environment of Neutron Stars

Abstract

Accreting X-ray Pulsars (XRPs) are some of the brightest X-ray sources in the sky, with widely varying intensities reaching upto a few Crabs. XRPs are binary stellar systems with a Neutron Star (NS) and a main sequence star. The NSs in these systems are highly magnetised (B ∼ 1012G) and are powered by matter accreted from the companion. Some details of the vicinity of the NS and the wider binary environment can be studied from the temporal and spectral properties of the X-ray emitted from these systems. In the first part of the thesis, results from an investigation of the binary environment in HMXB pulsar using fluorescent emission lines are presented. The strong iron fluorescent line in GX 301-2 is a tracer of the reprocessing environment. We look for temporal signatures in the iron fluorescence emission lines which can originate from any inhomogeneous and anisotropic matter distribution near the NS. The second part of the thesis is about the reprocessed emission from the shock forming region in the accretion column in X-ray binary pulsars, where the cyclotron lines are theorized to originate. Be XRPs, a subclass of XRPs, are known to exhibit a wide range in luminosity providing an ideal system to study the luminosity dependence of cyclotron lines. We study CRSF features in multiple Be-XRPs during their outburst phase to study how the line forming region in these systems depend on luminosity.