Abstract

The Event Horizon Telescope (EHT) has provided stunning images of the immediate vicinity of two supermassive black holes, M87* and Sgr A*, revealing the plasma swirling around them. To understand the complex emission observed, researchers have turned to general relativistic magnetohydrodynamic (GRMHD) simulations, which model the plasma as a fluid. These simulations have been successful in reproducing some features of the EHT images, but they rely on assumptions that do not apply in the low-density, high-magnetic-field environments around these black holes. General relativistic particle-in-cell (GRPIC) simulations offer a first-principles approach to modeling this environment, but their application to global black hole systems requires a suitable initial condition. The standard initial condition used in GRMHD simulations is a fluid equilibrium that collapses when evolved with kinetic physics, making it unsuitable for GRPIC simulations. This motivates the construction of a novel analytic collisionless equilibrium torus, which provides a realistic starting point for global collisionless accretion studies. Using this equilibrium, we present the first global GRPIC simulations of finite-angular-momentum accretion onto a spinning black hole. We find that the flow settles into a magnetically arrested state that closely resembles the fluid picture, with small-scale plasma instabilities providing effective collisionality. Most strikingly, the simulations show that the black hole's jet launches only when its magnetosphere is supplied with plasma by pair production: without it, the polar funnel stays empty and no jet forms.

Committee Chair

Yajie Yuan

Committee Members

Alexander Chen; Jason Dexter; Manel Errando; Michael Nowak

Degree

Doctor of Philosophy (PhD)

Author's Department

Physics

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

8-1-2026

Language

English (en)

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