Quantum evolution of de Sitter black holes near extremality

TL;DR

This paper investigates the quantum evolution of near-extremal charged de Sitter black holes, revealing they tend toward thermal equilibrium with the cosmological horizon rather than extremality, with unique energy transfer behaviors.

Contribution

It introduces a coupled Schwarzian and de Sitter quantum field theory framework to analyze quantum energy transfer near extremal de Sitter black holes, highlighting differences from flat space predictions.

Findings

Black holes evolve towards thermal equilibrium with the cosmological horizon.

Energy transfer rates differ from Hawking's thermal predictions.

Hotter black holes emit energy at lower rates, colder ones absorb energy steadily.

Abstract

We study the evolution of charged, asymptotically de Sitter black holes close to the cold extremal branch of the phase space. We consider black hole sizes that are parametrically smaller than both their inverse temperature and the cosmological horizon. Unlike flat space, charged de Sitter black holes do not evolve towards extremality, but rather towards a thermal equilibrium with the cosmological horizon. In the low-temperature regime, the near-horizon physics can be effectively captured by a one-dimensional Schwarzian theory. This is coupled to the far-horizon de Sitter quantum field theory. Incorporating the thermal nature of the cosmological horizon, we compute the quantum energy transfer through uncharged massless scalar particles. The results significantly differ from Hawking's thermal predictions. Black holes that are hotter than the cosmological horizon emit energy at a rate lower than their asymptotically flat counterparts. Whereas much colder ones absorb energy at a nearly constant rate.