Non-extremal Black Hole Microstates: Fuzzballs of Fire or Fuzzballs of Fuzz ?

TL;DR

This paper constructs near-extremal black hole microstate geometries using metastable supertubes, revealing potential observable differences from classical black holes and implications for singularity resolution.

Contribution

First family of microstate geometries for near-extremal black holes using metastable supertubes within smooth microstate backgrounds.

Findings

Microstate geometries differ from classical black holes at the horizon scale.

Fluctuations between fuzzballs can produce observable thermal noise.

Solutions suggest singularity resolution extends to the outer horizon.

Abstract

We construct the first family of microstate geometries of near-extremal black holes, by placing metastable supertubes inside certain scaling supersymmetric smooth microstate geometries. These fuzzballs differ from the classical black hole solution macroscopically at the horizon scale, and for certain probes the fluctuations between various fuzzballs will be visible as thermal noise far away from the horizon. We discuss whether these fuzzballs appear to infalling observers as fuzzballs of fuzz or as fuzzballs of fire. The existence of these solutions suggests that the singularity of non-extremal black holes is resolved all the way to the outer horizon and this "backwards in time" singularity resolution can shed light on the resolution of spacelike cosmological singularities.