Radiative magnetohydrodynarnic shocks around Kerr black holes

We study radiative magnetohydrodynamic (MHD) shocks in the accretion flow around a Kerr black hole for both the polar region and the equatorial region. The energy and the angular momentum across the radiative shocks are not conserved and are radiated away. We first present the formalisms of the radiative shock solutions in trans-magnetosonic flows by using the flux four-vector in the energy-momentum tensor. Automatic searching procedures for solutions giving many solutions for given boundary conditions are also presented. These procedures enable us to search all possible solutions. We next investigate the effects of radiation on the magnetohydrodynamic shocks. We find that a toroidal magnetic field is generated at the radiative shock as a back-reaction to the radiation even when only poloidal magnetic field is considered outside the shock region. The poloidal magnetic field is also changed by the radiation at the shocks, and the location of the Alfven point in the downstream region at the radiative shock is altered by radiation effects. Finally, we apply our calculations to the case of a massive black hole in a galactic center by considering radiation mechanisms, such as synchrotron radiation, bremsstrahlung, and gamma-ray radiation, due to decays of pions produced by proton collisions. We show that MHD shock formation can be a possible mechanism for X-ray and gamma-ray radiation. By solving the radiative transfer equation in the Kerr geometry, we calculate apparent images of the radiative shocks formed in the polar region in the vicinity of a black hole. We call such polar emission the black hole "aurora."