Seminaria

"Accretion Geometry of Black Hole X-ray Binaries in the Hard State"

Swadesh Chand (Inter-University Centre for Astronomy and Astrophysics, India)

Staszku, Podaję. Title: Accretion Geometry of Black Hole X-ray Binaries in the Hard State Abstract: Black hole X-ray binaries (BHXRBs) serve as ideal laboratories for studying the complex interplay between accretion and ejection processes in strong gravitational fields. Most of the low-mass BHXRBs are transient in nature and exhibit sporadic outbursts. During a typical outburst, these systems transition through various spectral states, from hard to soft, each associated with distinct spectral and timing properties. Despite decades of studies, the exact physical picture of these systems in the hard spectral state remains an open question, particularly regarding the geometry of the corona and extent of the inner accretion disk. While some studies argue for a disk that extends close to the innermost stable circular orbit (ISCO) in the hard state, others propose a significantly truncated disk scenario. In this talk, I will present findings from some of our recent broadband spectral and timing studies of BHXRBs in their hard state, which provide insights into the nature and evolution of the inner accretion flow.