Standing shocks in magnetized advection accretion flows onto a rotating black hole

TL;DR

This paper investigates the formation and properties of standing shocks in magnetized, advective accretion flows around rotating black holes, emphasizing the effects of dissipation, magnetic fields, and black hole spin on shock dynamics.

Contribution

It presents a comprehensive analysis of shock formation in magnetized accretion flows with dissipation, including the effects of black hole rotation and magnetic dominance, which was not extensively studied before.

Findings

Standing shocks can form in both gas and magnetic pressure dominated flows.

Shock formation persists even at high dissipation levels and around rapidly rotating black holes.

Maximum energy dissipation in the post-shock region is quantified and discussed in astrophysical context.

Abstract

We present the global structure of magnetized advective accretion flow around the rotating black holes in presence of dissipation. By considering accretion flow to be threaded by toroidal magnetic fields and by assuming synchrotron radiative mechanism to be the dominant cooling process, we obtain global transonic accretion solutions in terms of dissipation parameters, such as viscosity ($\alpha_B$), accretion rate (${\dot m}$) and plasma-$\beta$, respectively. In the rotating magnetized accretion flow, centrifugal barrier is developed in the nearby region of the black hole that triggers the discontinuous shock transition in the flow variables. Evidently, the shock properties and the dynamics of the post-shock flow (hereafter post-shock corona (PSC)) are being governed by the flow parameters. We study the role of dissipation parameters in the formation of standing shock wave and find that global shocked accretion solutions exist both in gas pressure dominated flows and in magnetic pressure dominated flows. In addition, we observe that standing shock continues to form around the rapidly rotating black holes as well. We identify the range of dissipation parameters that permits shocked accretion solutions and find that standing shocks continue to form even in presence of high dissipation limit, although the likelihood of shock formation diminishes with the increase of dissipation. Further, we compute the critical accretion rate (${\dot m}^{\rm cri}$) that admits shock and observe that standing shock exists in a magnetically dominated accretion flow when the accretion rate lies in general in the sub-Eddington domain. At the end, we calculate the maximum dissipated energy that may be escaped from the PSC and indicate its possible implication in the astrophysical context.