Sci.China Phys.Mech.Astron. 65, 120413 (2022)

Tightening the Penrose inequality

Hossein Khodabakhshi¹, Hong Lü¹ and Run-Qiu Yang¹

1 Center for Joint Quantum Studies, Department of Physics, School of Science, Tianjin University, Tianjin 300350, China.

* aqiu@tju.edu.cn

Abstract

The Penrose inequality estimates the lower bound of the mass of a black hole in terms of the area of its horizon. This bound is relatively loose for extremal or near extremal black holes. We propose a new Penrose-like inequality for static black holes involving the mass, area of the black hole event horizon and temperature. Our inequality includes the Penrose inequality as its corollary, and it is saturated by both the Schwarzschild and Reissner-Nordstr¨om black holes. In the spherically-symmetric case, we prove this new inequality by assuming both the null and trace energy conditions.