Null energy condition of dynamical black holes in spatially flat FLRW space-times

TL;DR

This paper introduces a new identity to analyze the null energy condition in dynamical black hole models within FLRW space-times, demonstrating that physically meaningful models have horizons evolving consistently with black hole theory.

Contribution

It presents a novel identity for applying the null energy condition to recent dynamical black hole models in cosmological backgrounds.

Findings

The new identity helps identify physically meaningful black hole models.

Models satisfying the null energy condition have horizons evolving as per black hole theory.

The study links horizon evolution with the null energy condition in dynamical black holes.

Abstract

A new identity reported here for the first time is used for studying how the null energy condition can be applied to the models of dynamical black holes proposed recently [I. I. Cot\u aescu, Eur. Phys. J. C (2022) 82:86]. It is shown that this condition selects the models with physical meaning whose horizons evolve in accordance with the general black hole theory in frames with null coordinates [S. A. Hayward, Phys. Rev. D {\bf 49} (1994) 6467].