Structural aspects of asymptotically safe black holes

TL;DR

This paper investigates quantum modifications of Schwarzschild (Anti-) de Sitter black holes using Quantum Einstein Gravity, revealing the cosmological constant's key role in short-distance structure and showing black holes evaporate completely without remnants.

Contribution

It demonstrates that the cosmological constant governs the UV structure of quantum black holes and connects thermodynamic entropy with quantum fluctuations.

Findings

Quantum effects are driven by the cosmological constant.

Asymptotic safety leads to complete black hole evaporation.

Entropy matches microstate count from quantum fluctuations.

Abstract

We study the quantum modifications of classical, spherically symmetric Schwarzschild (Anti-) de Sitter black holes within Quantum Einstein Gravity. The quantum effects are incorporated through the running coupling constants $G_k$ and $\Lambda_k$, computed within the exact renormalization group approach, and a common scale-setting procedure. We find that, in contrast to common intuition, it is actually the cosmological constant that determines the short-distance structure of the RG-improved black hole: in the asymptotic UV the structure of the quantum solutions is universal and given by the classical Schwarzschild-de Sitter solution, entailing a self-similarity between the classical and quantum regime. As a consequence asymptotically safe black holes evaporate completely and no Planck-size remnants are formed. Moreover, the thermodynamic entropy of the critical Nariai-black hole is shown to agree with the microstate count based on the effective average action, suggesting that the entropy originates from quantum fluctuations around the mean-field geometry.