Black-Hole Entropy from Supergravity Superstrata States

TL;DR

This paper investigates superstrata in string theory, showing that their supergravity solutions can account for a significant portion of black hole entropy through shape and density mode fluctuations, and proposes a link to dual CFT states.

Contribution

It provides evidence that superstratum fluctuations can reproduce black hole entropy growth and suggests a connection between superstrata bound states and dual CFT excitations.

Findings

Shape modes account for at least 1/√6 of the black hole entropy.

Supergravity fluctuations can reproduce entropy growth with charges.

Proposes a link between superstrata bound states and dual CFT sectors.

Abstract

There are, by now, several arguments that superstrata, which represent D1-D5-P bound states that depend upon arbitrary functions of two variables and that preserve four supersymmetries, exist in string theory, and that their gravitational back-reaction results in smooth horizonless solutions. In this paper we examine the shape and density modes of the superstratum and give strong evidence that the back-reacted supergravity solution allows for fluctuation modes whose quantization reproduces the entropy growth of black holes as a function of the charges. In particular, we argue that the shape modes of the superstratum that lie purely within the non-compact space-time directions account for at least $1/\sqrt{6}$ of the entropy of the D1-D5-P black hole and propose a way in which the rest of the entropy could be captured by superstratum fluctuations. We complete the picture by conjecturing a relationship between bound states of multiple superstrata and momentum excitations of different twisted sectors of the dual CFT.