Polarization Whorls from M87 at the Event Horizon Telescope

Delilah Gates, Daniel Kapec, Alexandru Lupsasca, Yichen Shi, Andrew Strominger

Published 2018-09-24Version 1

The Event Horizon Telescope (EHT) is expected to soon produce polarimetric images of the supermassive black hole at the center of the neighboring galaxy M87. This black hole is believed to be very rapidly spinning, within 2% of extremality. General relativity predicts that such a high-spin black hole has an emergent conformal symmetry near its event horizon. In this paper, we use this symmetry to analytically predict the polarized near-horizon emissions to be seen at the EHT and find a distinctive pattern of whorls aligned with the spin.