Criticality in the collapse of spherically symmetric massless scalar fields in semi-classical loop quantum gravity

TL;DR

This paper investigates the critical phenomena in gravitational collapse of scalar fields within semi-classical loop quantum gravity, providing evidence for self-similar solutions and analyzing their properties.

Contribution

It offers new evidence for the existence of self-similar critical solutions in semi-classical loop quantum gravity and explores their characteristics using adaptive mesh refinement.

Findings

Existence of self-similar critical solutions confirmed.

Observation of echoes due to discrete self-similarity.

Mass scaling relations show wiggles similar to classical theory.

Abstract

In a recent paper we showed that the collapse to a black hole in one-parameter families of initial data for massless, minimally coupled scalar fields in spherically symmetric semi-classical loop quantum gravity exhibited a universal mass scaling similar to the one in classical general relativity. In particular, no evidence of a mass gap appeared as had been suggested by previous studies. The lack of a mass gap indicated the possible existence of a self-similar critical solution as in general relativity. Here we provide further evidence for its existence. Using an adaptive mesh refinement code, we show that "echoes" arise as a result of the discrete self-similarity in space-time. We also show the existence of "wiggles" in the mass scaling relation, as in the classical theory. The results from the semi-classical theory agree well with those of classical general relativity unless one takes unrealistically large values for the polymerization parameter.