Extremal Instability for Topological Black Holes

TL;DR

This paper explores the instability of extremal black holes in the context of holography, predicting a lower bound on cold strongly coupled matter densities, supported by neutron star observations.

Contribution

It applies the Weak Gravity Conjecture to planar AdS black holes, deriving a novel lower bound on matter density through gauge-gravity duality.

Findings

Predicted a lower bound on cold matter density in holographic models.

Supported the bound with neutron star core density observations.

Linked black hole instability to properties of dense matter in astrophysics.

Abstract

The initial idea underlying the Weak Gravity Conjecture is that extremal black holes must always be "unstable", in the sense that they should slowly decay by emitting either particles or smaller black holes. Here we show that, when this idea is applied to the \emph{planar} asymptotically AdS black holes which play a central role in applications of holography, the result, via gauge-gravity duality, is a prediction that there should exist a lower bound on the possible densities of cold strongly coupled matter. Recent observations of neutron stars suggest that, in many cases, even the extreme densities in their cores may not be sufficient to generate quark matter, showing that there is indeed a (very high) lower bound on the possible density of cold quark matter.