Towards the most realistic radiative models of luminous black hole accretion.

Black holes (BHs) are typically surrounded by plasma (a tenuous, hot gas of charged particles) that accretes onto them, i.e. falls inward. As accretion proceeds, plasmas are heated and emit light, which we observe on Earth. Most studies of BHs focus on a minority population of luminous BHs. Even for these luminous BHs, we have reliable interpretive tools only for the dense emitting gas. Interpreting emission from low-density, optically thin and/or collisionless regions requires modeling processes at both the macro-scale of the accretion flow and the micro-scale of the particles ultimately radiating. In this proposal, I explain how I will create the most realistic radiative models of luminous BHs to date, including the low-density regions that produce the highest energy emission, by developing a new version of the public code BHAC able to self-consistently treat the physics at the fluid scale and the particle scale using the best radiation treatment in the community. This work represents a huge step towards the resolution of outstanding problems such as spectral state changes in BHs, jet formation in luminous disks or the origin of quasi-periodic oscillations but will also revolutionize interpretative tools using fast variability and polarization measurements. These revolutionary methods will help interpreting existing and future observations from missions such the all-sky X-ray survey eROSITA, the  gamma-ray detector CTA, and the X-ray polarimeters IXPE and eXTP.

Keywords:Accretion and Black Holes, High Energy Astro- and Plasma physics, Fluid, Radiative, Numerical simulations

Disciplines:Numerical computation, General relativity and gravitation, High energy astrophysics, astroparticle physics and cosmic rays, Time-domain astrophysics, Physics of gases, plasmas and electric discharges not elsewhere classified