Adiabatic accretion onto black holes in Einstein-Maxwell-scalar theory

TL;DR

This paper investigates how baryonic gas accretes onto spherically symmetric black holes within Einstein-Maxwell-scalar theory, analyzing the effects of coupling parameters on accretion dynamics, transonic points, and temperature ratios.

Contribution

It introduces the influence of two coupling parameters on accretion processes and modifies the mass accretion rate and temperature ratios in Einstein-Maxwell-scalar black holes.

Findings

Range of transonic points depends on charge-to-mass ratio and radius.

Coupling parameters affect mass accretion rate at different sound speed orders.

Temperature ratios of accreted gas are altered by the coupling parameters.

Abstract

We study the adiabatic accretion process of ordinary baryonic gas onto spherically symmetric black holes in Einstein-Maxwell-scalar theory, with two parameters $\alpha$ and $\beta$ in the coupling term. Especially, we demonstrate the range of the transonic points in terms of the charge-to-mass ratio squared and the dimensionless coordinate radius, in two important classes of black holes as examples. Further, we find that the two coupling parameters give modifications to the mass accretion rate at different orders of the sound speed at infinity. We also present their different effects on the temperature ratios of the accreted gas.