Seminars

"Eclipse does not hide but reveals: Comprehensive X-ray Reprocessing Studies in High and Low Mass X-ray Binaries with XMM-Newton"

Nafisa Aftab (Raman Research Institute)

X-ray reprocessing serves as a vital diagnostic tool for gaining insights into the environments of X-ray binary systems. However, the study of X-ray reprocessing encounters challenges arising from the blending of intense primary radiation from the compact star with the reprocessed radiation from the surrounding. Eclipsing X-ray binaries offer a unique opportunity to investigate pure reprocessed X-rays, as the companion star effectively shields the intense primary X-rays during eclipse. We carried out comprehensive studies of X-ray reprocessing in several eclipsing High Mass X-ray Binary (HMXB) and Low Mass X-ray Binary (LMXB) systems by comparing their X-ray spectra during and outside of eclipse using XMM-Newton. We found ample diversity in the X-ray reprocessing characteristics in HMXBs, which implies significantly dynamic wind structure surrounding the compact objects in HMXBs. Even in the same source at different epochs, the variation is quite large. Significant differences observed in X-ray reprocessing characteristics in LMXBs too, despite all being dipping and eclipsing sources, suggest large dependencies of X-ray reprocessing in LMXBs on the inclination angle, scale height of the accretion disk, relative size of the accretion disk with respect to the companion, binary separation and many other known and unknown factors. Overall the studies deepen our understanding of the intricate interplay between X-ray reprocessing and the diverse mechanisms within X-ray binary systems. In these studies we have also observed some unexpected behaviours of the X-ray binaries and the exact reason of which is not yet clear. We anticipate that discussion with you all will illuminate these unexpected behaviors in X-ray binaries and inspire numerous new avenues for future research on these intriguing systems.