Astrophysics, Relativity, and Cosmology Seminar - Lizhong Zhang (Flatiron Institute) "Modeling Black Hole Accretion with Radiation GRMHD: A Parameter Survey and Connection to Observations"
Speaker: |
(sign-up)
Lizhong Zhang, Flatiron Institute |
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Date: | 4/30/2025 |
Time: | 12 p.m. |
Location: | Rhondale Tso Seminar Room, Loomis 236 |
Event Contact: | Deanna Frye ddebord@illinois.edu |
Sponsor: | Department of Physics |
Event Type: | Seminar/Symposium |
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. |