Invited Talk - Splinter Compact
EHT Black Hole Observations Constraining Models of Gravity
Michael F. Wondrak
Radboud Universiteit Nijmegen
With an array of radio telescopes distributed all over the world, the Event Horizon Telescope collaboration succeeded in resolving the shadows of black holes for the first time. Having the largest angular diameter, the supermassive black holes observed are located in the center of galaxies: M87* in M87 and Sgr A* in our Milky Way. This talk is devoted to the gravitational physics implications of the observations. We explain the origin of black hole shadows and their features. In particular, the ring diameter is shown to be suited for tests of gravity. We contrast the predictions by general relativity and by generalized gravitational theories with the EHT observations and derive bounds on alternative compact objects. Finally, we investigate the observability of quantum gravity corrections for the case of quadratic gravity.