Princeton University Gravity Initiative Fall Seminar Series
Spin Signatures in VLBI Images of Supermassive Black Hole Accretion Flows
Abstract: The Event Horizon Telescope has released total intensity images of the Messier 87* and Sagittarius A* accretion flows; polarized images have been released for M 87*, and are imminent for Sgr A*. These images are a rich source of theoretical constraints on the black hole accretion flow system, but a trustworthy measurement of either black hole's spin remains elusive. Spin nonetheless remains a high priority, as the black hole angular momentum is deeply linked to mechanisms of energy extraction and galactic co-evolution. In my talk, I will discuss my work on providing theoretical traction on supermassive black hole spin, and will review the state of spin measurements using existing and future ETH data, including measurements of the black hole photon ring, inference of near-horizon magnetic field structure, and next-generation spacetime/emissivity inference codes.