Spectral radiative transfer post-processing of GRMHD simulations of black hole accretion with Christopher Naegle

Spectral observations of accreting black holes are one of our most powerful tools for understanding these enigmatic objects. Black hole spectra contain complex phenomenology, including quasi-thermal components, power law components, broadened emission lines and spectral state transitions in stellar mass black holes (but not supermassive ones). Relating these spectra to simulations, however, has proven challenging given the many radiative processes at play. We present radiative transfer post-processing of three dimensional general relativistic magnetohydrodymanic (GRMHD) simulations. We partition simulations into an optically thin corona, in which we solve the radiative transfer problem using a relativistic Monte-Carlo code, and an optically thick diskbody, in which we solve for the radiation field and for ionization balance using a Feautrier solver. Each of these two codes provides the radiative boundary condition for the other, allowing us to solve for thermal balance throughout the entire system, accounting for all relativistic and radiative effects. We discuss the dependence of our predicted spectra on black hole mass, the origin of broadened Fe K$\alpha$ emission lines in our calculations, and the behavior of polarized X-rays.

Sponsored by the McDonnell Center for the Space Sciences