Black Hole Metamorphosis and Stabilization by Memory Burden

Abstract

Systems of enhanced memory capacity are subjected to a universal effect of memory burden, which suppresses their decay. In this paper, we study a prototype model to show that memory burden can be overcome by rewriting stored quantum information from one set of degrees of freedom to another one. However, due to a suppressed rate of rewriting, the evolution becomes extremely slow compared to the initial stage. Applied to black holes, this predicts a metamorphosis, including a drastic deviation from Hawking evaporation, at the latest after losing half of the mass. This raises a tantalizing question about the fate of a black hole. As two likely options, it can either become extremely long lived or decay via a new classical instability into gravitational lumps. The first option would open up a new window for small primordial black holes as viable dark matter candidates.

Comments: 24 pages (2 column), 8 figures, 1 appendix; v2: added discussions of analytic understanding of our result (section III.C) and of role of number non-conservation (section IV) as well as minor improvements, matches published version; v3: added link to numerical data, minor updates of references and plots