Testing General Relativity with the Shadow Size of Sgr A*

Citation:

Tim Johannsen, Avery E. Broderick, Philipp M. Plewa, Sotiris Chatzopoulos, Sheperd S. Doeleman, Frank Eisenhauer, Vincent L. Fish, Reinhard Genzel, Ortwin Gerhard, and Michael D. Johnson. 2016. “Testing General Relativity with the Shadow Size of Sgr A*.” Physical Review Letters, 116.

Abstract:

In general relativity, the angular radius of the shadow of a black holeis primarily determined by its mass-to-distance ratio and depends onlyweakly on its spin and inclination. If general relativity is violated,however, the shadow size may also depend strongly on parametricdeviations from the Kerr metric. Based on a reconstructed image ofSagittarius A* (Sgr A* ) from a simulated one-dayobserving run of a seven-station Event Horizon Telescope (EHT) array, weemploy a Markov chain Monte Carlo algorithm to demonstrate that such anobservation can measure the angular radius of the shadow of Sgr