For the first time, horizon scale structure around a supermassive black hole was imaged with the EventHorizonTelescope.
In this talk, I will discuss the physical interpretation of the ring-like structure emerging in the center of the galaxy M87. To compare the observations with theoretical expectations, a library of ~60000 theoretical images was obtained from 3D GRMHD simulations with different black hole spins, masses and orientations. The data is consistent with most simulations of a radiatively inefficient accretion flow and yields a black hole mass of 6.5x10^9 Msun, in excellent agreement with the stellar dynamical measurement.
Further firm parameter constraints are currently thwarted by the stochastic nature of the underlying models as well as the uncertain modeling of electron physics in near collision-less regimes. More constraints are set by including multi-wavelength data and by using limits on the jet power.
I will also briefly discuss implications to alternatives to GR and future prospects for physics with the EHT.
Local contact, organization: M. Bugli