Horizon divergences of Fields and Strings in Black Hole backgrounds

TL;DR

This paper explores the universal boundary divergences in thermodynamic quantities near black hole horizons, their interpretation as infrared effects, and their implications for string theory and gravitational stability.

Contribution

It demonstrates the universality of intensive thermodynamic quantities near horizons and discusses their infrared nature and potential resolution in string theory.

Findings

Boundary divergences follow Hawking-Bekenstein form

Intensive quantities are universal near horizons

Divergences may indicate gravitational instabilities

Abstract

General arguments based on curved space-time thermodynamics show that any extensive quantity, like the free energy or the entropy of thermal matter, always has a divergent boundary contribution in the presence of event horizons, and this boundary term comes with the Hawking-Bekenstein form. Although the coefficients depend on the particular geometry we show that intensive quantities, like the free energy density are universal in the vicinity of the horizon. {} From the point of view of the matter degrees of freedom this divergence is of infrared type rather than ultraviolet, and we use this remark to speculate about the fate of these pathologies in String Theory. Finally we interpret them as instabilities of the Canonical Ensemble with respect to gravitational collapse via the Jeans mechanism.