Radiative Magnetohydrodynamic Shocks Around Kerr Black Holes

다국어 초록 (Multilingual Abstract)

We study radiative magnetohydrodynamic (MHD) shocks in the accretion °ow around a Kerr
black hole for both the polar region and the equatorial region. The energy and the angular mo-
mentum across the radiative shocks are not conserved and are radiated away. We .rst present
the formalisms of the radiative shock solutions in trans-magnetosonic °ows by using the °ux 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 eects of radiation on the magnetohydrodynamic
shocks. We .nd that a toroidal magnetic .eld is generated at the radiative shock as a back-reaction
to the radiation even when only poloidal magnetic .eld is considered outside the shock region.
The poloidal magnetic .eld is also changed by the radiation at the shocks, and the location of the
Alfv¶en point in the downstream region at the radiative shock is altered by radiation eects. 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."

참고문헌 (Reference)

1 "ArXiv:astro-ph/0509237" 2005