Study of relativistic accretion flow in the $f(R)$ theory of gravity

TL;DR

This paper investigates relativistic accretion flows within an $f(R)$ gravity framework, analyzing how modifications to gravity influence flow properties, critical points, and luminosity, with implications for accretion disk observations.

Contribution

It provides a detailed analysis of accretion flow solutions in $f(R)$ gravity, including the effects of gravity parameters on critical points and luminosity, extending understanding beyond general relativity.

Findings

Flow can have single or multiple critical points depending on parameters.

The parameter space for accretion solutions shrinks with decreasing $A$ and vanishes at $A=-2.34$.

Inner critical point solutions are more luminous than outer critical point solutions.

Abstract

We present the properties of relativistic, inviscid, low angular momentum, advective accretion flow in a $f(R)$ gravity theory that satisfactorily mimics the asymptotically flat vacuum solutions of the Einstein's equations. With this, we solve the governing equations describing the accretion flow and obtain the global transonic accretion solutions in terms of flow energy (${\cal E}$), angular momentum ($\lambda$) and gravity parameter ($A$) that determines the effect of $f(R)$ gravity. We observe that depending on the model parameters, flow may contain either single or multiple critical points. We separate the effective domain of the parameter space in $\lambda-{\cal E}$ plane that admits accretion solutions possessing multiple critical points and observe that solution of this kind continues to form for wide range of the flow parameters. We examine the modification of the parameter space and reveal that it gradually shrinks with the decrease of $A$, and ultimately disappears for $A=-2.34$. Finally, we calculate the disk luminosity ($L$) considering bremsstrahlung emission process and find that global accretion solutions passing through the inner critical point are more luminous compared to the outer critical point solutions.