Half the Schwarzschild Entropy from Strominger-Vafa Black Holes

TL;DR

This paper constructs a regular bound state of extremal black holes in string theory that mimics Schwarzschild black holes and explores its entropy, suggesting a brane/antibrane interpretation of Schwarzschild entropy.

Contribution

It introduces a new bound state of extremal black holes in string theory with a microscopic entropy description matching half of Schwarzschild entropy.

Findings

Bound state resembles Schwarzschild black hole asymptotics.

Entropy approaches half of Schwarzschild entropy at large mass.

Provides a potential brane/antibrane explanation for Schwarzschild entropy.

Abstract

We construct a regular bound state of two extremal black holes in type IIB supergravity with opposite charges. The bound state resembles the Schwarzschild black hole from the asymptotics to the photon ring and has the same mass and charges as the Schwarzschild black hole. On the one hand, we show that the bound-state entropy admits a microscopic description in terms of branes and antibranes in string theory. On the other hand, we demonstrate that the entropy approaches half of the Schwarzschild entropy as the mass becomes significantly larger than the Kaluza-Klein scales used to regularize the geometry. This opens up the possibility of a brane/antibrane interpretation of the Schwarzschild entropy in string theory.