Testing the theory of gravity with the GRMHD simulation and black hole Imaging

Accretion physics has become more important recently due to the detection of the first horizon-scale images of the supermassive black holes of M 87∗ and Sgr A∗ by the Event Horizon Telescope (EHT). General relativistic magnetohydrodynamic (GRMHD) simulations of magnetized accretion flows onto a Kerr black hole have been used to interpret them. However, further testing the theory of gravity by using horizon-scale images requires performing consistent GRMHD simulations in non-Kerr spacetime. This talk will be mainly focused on the validity of gravity theories around compact objects from current and future observations with the help of GRMHD and GRRT simulations.