Zachary Gelles and Jayke Nguyen

From the calendar

Supermassive black holeslaunch luminous, relativistic jets that are observed at parsec-level scales.While black hole spin is believed to play an important role in powering thesejets, the spin parameter has proven difficult to measure directly. In thistalk, I will discuss how black hole spin imprints itself on surroundingmagnetic fields, yielding a new observable signature of spin. Specifically, Iwill show how black hole spin “winds up” the magnetic field at criticalsurfaces called light cylinders, where plasma begins to accelerate into aninflow or an outflow. Using a combination of semi-analytic models and numericalsimulations, I will then demonstrate that this wind-up translates into spatialpolarization swings in the emission, which can be observed through radiointerferometry. This technique would allow us to constrain supermassive blackhole spins and jet Lorentz factors with forthcoming observations of severalnearby AGN.