Speaker
Description
Accretion onto stellar-mass black holes in X-ray binaries produces diverse spectral and temporal behaviour across the electromagnetic spectrum. The ultraviolet (UV) and X-ray bands are particularly powerful diagnostics, directly probing the outer accretion disk, the hot inner flow and corona, and disk–wind interactions.
In this work, we present a comprehensive UV–X-ray spectral study of black hole X-ray binaries using simultaneous and quasi-simultaneous observations from space-based observatories. The combined datasets provide broadband coverage from the outer disk to regions close to the event horizon. We model the spectra with physically motivated accretion frameworks that incorporate multi-temperature disk emission, Comptonization in a hot corona, and reprocessing and absorption by disk winds.
This approach enables us to track the evolution of key accretion parameters—including mass accretion rate, inner disk radius, coronal temperature, and optical depth—across spectral states and luminosity regimes. We find that UV emission places strong constraints on outer disk structure and irradiation, while X-ray spectra probe the geometry and energetics of the inner accretion flow. By linking UV and X-ray diagnostics within a unified framework, we provide new insights into disk–corona coupling, state transitions, and the role of outflows in shaping the accretion environment of black hole X-ray binaries.