Testing General Relativity with the Shadow Size of Sgr
Author(s)Johannsen, Tim; Broderick, Avery E.; Plewa, Philipp M.; Chatzopoulos, Sotiris; Eisenhauer, Frank; Genzel, Reinhard; Gerhard, Ortwin; Johnson, Michael D.; Doeleman, Sheperd Samuel; Fish, Vincent L.; ... Show more Show less
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In general relativity, the angular radius of the shadow of a black hole is primarily determined by its mass-to-distance ratio and depends only weakly on its spin and inclination. If general relativity is violated, however, the shadow size may also depend strongly on parametric deviations from the Kerr metric. Based on a reconstructed image of Sagittarius A∗ (Sgr A∗) from a simulated one-day observing run of a seven-station Event Horizon Telescope (EHT) array, we employ a Markov chain Monte Carlo algorithm to demonstrate that such an observation can measure the angular radius of the shadow of Sgr A∗ with an uncertainty of ∼1.5 μas (6%). We show that existing mass and distance measurements can be improved significantly when combined with upcoming EHT measurements of the shadow size and that tight constraints on potential deviations from the Kerr metric can be obtained.
Physical Review Letters
American Physical Society
Johannsen, Tim et al. “Testing General Relativity with the Shadow Size of SgrA*.” Physical Review Letters 116, 3 (January 2016): 031101 © 2016 American Physical Society
Final published version