Quantum vacuum effects on the formation of black holes

TL;DR

This paper investigates how quantum vacuum effects influence black hole formation during dust shell collapse, revealing modifications to spacetime structure and conditions for non-singular black holes.

Contribution

It demonstrates that quantum effects can alter black hole horizons and potentially prevent singularity formation under specific conditions.

Findings

Quantum effects create dual horizons in black holes.

Collapse often results in singularities unless quantum effects induce a bounce.

Non-singular black holes can form with collapse halting before singularity.

Abstract

We study the backreaction of quantum fields induced through the vacuum polarization and the conformal anomaly on the collapse of a thin shell of dust. It is shown that the final fate of the collapse process depends on the physical properties of the shell, including its rest and gravitational masses. Investigating the conditions for the formation of black holes, we notice that quantum effects modify the geometry and structure of Schwarzschild space-time in such a way that black holes have two horizons, an inner and an outer horizon. If the gravitational mass of the shell is about that of an ordinary star, then in most cases, the semi-classical collapse will terminate in a singularity, and in general, quantum fluctuations are not strong enough to prevent the creation of the singularity. Although under certain conditions, it is possible to form a non-singular black hole, i.e., a regular black hole. In this way, the collapse stops at a radius much larger than the Planck length below the inner horizon, and the shell bounces and starts an expansion.