Global Three-Dimensional MHD Simulations of Co-existence of Hard State and Soft State Disks in Black Hole Accretion Flows

Abstract

We present the results of 3D global resistive magnetohydrodynamic (MHD) simulations of black hole accretion flows. General relativistic effects are simulated by using the pseudo-Newtonian potential. We included optically thin bremsstrahlung cooling to simulate the transition from low state to high state. We found that the outer disk cooled down by radiative cooling becomes dominated by magnetic pressure. Hard-state disks in the inner region co-exists with soft-state disks in the outer region. We computed radiation spectrum of the disk by including synchrotron emission and compton cooling, and reproduced the observed X-ray spectrum of black hole candidates.