TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 851 0756 7442

ABSTRACT: Supermassive black holes launch luminous, relativistic jets that are observed at parsec-level scales. While black hole spin is believed to play an important role in powering these jets, the spin parameter has proven difficult to measure directly. In this talk, I will discuss how black hole spin imprints itself on surrounding magnetic fields, yielding a new observable signature of spin. Specifically, I will show how black hole spin "winds up" the magnetic field at critical surfaces called light cylinders, where plasma begins to accelerate into an inflow or an outflow. Using a combination of semi-analytic models and numerical simulations, I will then demonstrate that this wind-up translates into spatial polarization swings in the emission, which can be observed through radio interferometry. This technique would allow us to constrain supermassive black hole spins and jet Lorentz factors with forthcoming observations of several nearby AGN.
Based on arXiv:2410.00954, arXiv:2601.13307, arXiv:2606.12518