General relativity and relativistic astrophysics

TL;DR

This paper reviews the role of general relativity in astrophysics, highlighting its enduring importance in explaining phenomena around black holes and discussing the need for modifications to Einstein's theory for certain astrophysical processes.

Contribution

It emphasizes the continued relevance of Einstein's solutions and discusses the necessity of modified theories of gravity to explain complex astrophysical phenomena.

Findings

Schwarzschild and Kerr solutions remain fundamental in astrophysics.

Modified gravity theories are needed for some modern astrophysical explanations.

General relativity is essential but not always sufficient for understanding compact objects.

Abstract

Einstein established the theory of general relativity and the corresponding field equation in 1915 and its vacuum solutions were obtained by Schwarzschild and Kerr for, respectively, static and rotating black holes, in 1916 and 1963, respectively. They are, however, still playing an indispensable role, even after 100 years of their original discovery, to explain high energy astrophysical phenomena. Application of the solutions of Einstein's equation to resolve astrophysical phenomena has formed an important branch, namely relativistic astrophysics. I devote this article to enlightening some of the current astrophysical problems based on general relativity. However, there seem to be some issues with regard to explaining certain astrophysical phenomena based on Einstein's theory alone. I show that Einstein's theory and its modified form, both are necessary to explain modern astrophysical processes, in particular, those related to compact objects.