Properties of the spherically symmetric polymer black holes

TL;DR

This paper explores a five-parameter class of spherically symmetric polymer black/white hole solutions, revealing diverse spacetime structures, including regular black holes, wormholes, and singular spacetimes, with quantum effects significant at horizons.

Contribution

It systematically analyzes the full phase space of these solutions, identifying three key physical parameters and their impact on spacetime properties, including the existence of horizons and singularities.

Findings

Regular black/white holes with non-zero throat radius

Wormhole-like solutions without horizons

Quantum effects remain significant at horizons for solar mass black holes

Abstract

In this paper we systematically study a five-parameters class of spherically symmetric polymer black/white hole solutions, and find that only three independent combinations are physical and uniquely determine the spacetime properties. After exploring the whole 3-dimensional (3D) phase space, we find that the model has very rich physics, and depending on the choice of these parameters, various possibilities exist, including: (i) spacetimes that have the standard black/white hole structures, that is, spacetimes that are free of spacetime curvature singularities and possess two asymptotically flat regions, which are connected by a transition surface (throat) with a finite and non-zero geometric radius. The black/white hole masses measured by observers in the two asymptotically flat regions are all positive, and the surface gravity of the black (white) hole is positive (negative). (ii) Spacetimes that have wormhole-like structures, in which the two masses are all positive, but no horizons exist.(iii) Spacetimes that still possess curvature singularities, which can be either hidden inside trapped regions or naked. However, such spacetimes correspond to only some limit cases, and the necessary (but not sufficient) condition is that at least one of the two "polymerization" parameters vanishes. In addition, even for solar mass black/white holes, quantum gravitational effects can be still very large at the black/white hole horizons, again depending on the choice of the parameters.