Properties of Two-Temperature Dissipative Accretion Flow Around Black Holes

TL;DR

This paper investigates two-temperature accretion flows around non-rotating black holes, revealing the existence of multi-transonic solutions with shock waves that could explain observed X-ray emissions.

Contribution

It introduces the first global two-temperature accretion solutions with standing shocks, considering dissipation effects and magnetic fields, expanding understanding of black hole accretion physics.

Findings

Solutions are multi-transonic, passing through inner and outer critical points.

Shock solutions exist over a wide parameter range, with the domain shrinking as dissipation increases.

Post-shock regions are hotter, emitting hard X-rays, relevant for black hole spectral modeling.

Abstract

We study the properties of two-temperature accretion flow around a non-rotating black hole in presence of various dissipative processes where pseudo-Newtonian potential is adopted to mimic the effect of general relativity. The flow encounters energy loss by means of radiative processes acted on the electrons and at the same time, flow heats up as a consequence of viscous heating effective on ions. We assumed that the flow is exposed with the stochastic magnetic fields which leads to Synchrotron emission of electrons and these emissions are further strengthen by Compton scattering. We obtain the two-temperature global accretion solutions in terms of dissipation parameters, namely, viscosity ($\alpha$) and accretion rate (${\dot m}$), and find for the first time in the literature that such solutions may contain standing shock waves. Solutions of this kind are multi-transonic in nature as they simultaneously pass through both inner critical point ($x_{\rm in}$) and outer critical point ($x_{\rm out}$) before crossing the black hole horizon. We calculate the properties of shock induced global accretion solutions in terms of the flow parameters. We further show that two-temperature shocked accretion flow is not a discrete solution, instead such solution exists for wide range of flow parameters. We identify the effective domain of the parameter space for standing shock and observe that parameter space shrinks as the dissipation is increased. Since the post-shock region is hotter due to the effect of shock compression, it naturally emits hard X-rays and therefore, the two-temperature shocked accretion solution has the potential to explain the spectral properties of the black hole sources.