Conceptual

Compton Down-Scattering of Accretion-Disk Radiation by Black-Hole Disk Winds in Astrophysics

In the high/soft state of a black-hole X-ray binary the thermal accretion-disk spectrum can be reprocessed by an overlying disk wind. Students learn how multi-dimensional Monte Carlo simulations show that a stratified wind of moderate-to-high density Compton down-scatters the disk photons, deforming the transmitted continuum away from the standard multi-color-disk shape, and why this scattering effect should be treated as a separate factor alongside the usual color-correction (hardening) factor, potentially biasing black-hole spin estimates from continuum fitting.