Properties of two-temperature magnetized advective accretion flow around rotating black hole

Abstract

We study the two-temperature magnetized advective accretion flow around the Kerr black holes (BHs). During accretion, ions are heated up due to viscous dissipation, and when Coulomb coupling becomes effective, they transfer a part of their energy to the electrons. On the contrary, electrons lose energy due to various radiative cooling processes, namely bremsstrahlung, synchrotron, and Comtonization processes, respectively. To account for the magnetic contribution inside the disc, we consider the toroidal magnetic fields which are assumed to be dominant over other components. Moreover, we adopt the relativistic equation of state to describe the thermal characteristics of the flow. With this, we calculate the global transonic accretion solutions around the rotating BHs. We find that accretion solution containing multiple critical points may harbour shock wave provided the standing shock conditions are satisfied. Further, we investigate the shock properties, such as shock location (xs) and compression ratio (R) that delineate the post-shock corona (hereafter PSC) and find that the dynamics of PSC is controlled by the flow parameters, such as accretion rate (m) and magnetic fields (β, defined as the ratio of gas pressure to the magnetic pressure), etc. Finally, we calculate the emission spectra of the accretion flows containing PSC and indicate that both m and β play the pivotal roles in explaining the spectral state transitions commonly observed for BH X-ray binaries. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society