Probing Axion Clouds with EHT Data Using Closure Trace Analyses

Ultralight axion-like particles could form clouds around spinning supermassive black holes and modulate the polarization of nearby emission. This seminar uses Event Horizon Telescope polarimetry of M87* and Sagittarius A* to constrain that possibility through closure-trace products designed to resist calibration errors. It compares the two sources and considers prospects for future EHT observations.