Magnetized Advective Accretion Disks and Jets: Harmpi Simulation

Abstract

An optically thin advective accretion disk appears to be indispensable to explain hard-state of black hole sources. Any transport of matter therein is assumed to be led by (modified) \(\alpha \)-viscosity when the magnetic field is weak. We explore how large scale stronger magnetic field helps in transporting angular momentum in disk and outflow/jet, depending on the field geometry and plasma-\(\beta \) parameter, basically by underlying magnetic shear over \(\alpha \)-viscosity. Interestingly, while above a critical accretion rate the accretion disk turns out to be thermally unstable, in the presence of stronger magnetic fields the disk regains its stability. In the present work, we establish this by numerical simulation based on HARMPI, while the underlying theory was established by one of us earlier. This magnetically arrested advective accretion disk (MA-AAF) in the optically thin regime has far reaching implications including the explanation of ultra-luminous X-ray sources.