Criticality In The Collapse Of Spherically Symmetric Massless Scalar Fields In Semiclassical Loop Quantum Gravity
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 semiclassical 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 semiclassical theory agree well with those of classical general relativity unless one takes unrealistically large values for the polymerization parameter.