TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 864 8902 5566

ABSTRACT: Radiation and magnetic fields play crucial roles in shaping black hole accretion across a wide range of regimes. To model these systems, we solve the GRMHD equations coupled with angle-dependent radiation transfer, which enables us to capture the complex dynamics of accretion in extreme environments — from super-Eddington to sub-Eddington regimes. In the super-Eddington regime, radiative support causes the accretion disk to thermally expand, forming a narrow conical funnel through which radiation escapes, leading to low radiation efficiency. In the sub- and near-Eddington regimes, the magnetic field topology strongly influences the resulting disk structure, allowing the system to reach a steady state as either a thin disk with magnetic coronae or a magnetically elevated disk. These simulations broadly align with observational findings — such as the soft states of X-ray binaries, ultraluminous X-ray sources, and "little red dots" — and offer predictive diagnostics for future observations, which I will discuss in detail during the talk.