Asymptotically flat vacuum solution in modified theory of Einstein's gravity

TL;DR

This paper demonstrates the existence of asymptotically flat vacuum solutions in f(R) gravity, differing from Schwarzschild, with applications to black hole orbits and accretion flows, challenging previous solutions with diverging terms.

Contribution

It introduces a new asymptotically flat vacuum solution in f(R) gravity, overcoming previous divergence issues and expanding understanding of black hole spacetimes.

Findings

Found asymptotically flat vacuum solutions in f(R) gravity

Applied solutions to bound orbits around black holes

Analyzed spherical accretion flows using the new solution

Abstract

A number of recent observations have suggested that the Einstein's theory of general relativity may not be the ultimate theory of gravity. The f(R) gravity model with R being the scalar curvature turns out to be one of the best bet to surpass the general relativity which explains a number of phenomena where Einstein's theory of gravity fails. In the f(R) gravity, behaviour of the spacetime is modified as compared to that of given by the Einstein's theory of general relativity. This theory has already been explored for understanding various compact objects such as neutron stars, white dwarfs etc. and also describing evolution of the universe. Although, researchers have already found the vacuum spacetime solutions for the f(R) gravity, yet there is a caveat that the metric does have some diverging terms and hence these solutions are not asymptotically flat. We show that it is possible to have asymptotically flat spherically symmetric vacuum solution for the f(R) gravity, which is different from the Schwarzschild solution. We use this solution for explaining various bound orbits around the black hole and eventually, as an immediate application, in the spherical accretion flow around it.