Black Holes in the Universe: Generalized Lemaitre-Tolman-Bondi Solutions

TL;DR

This paper introduces new exact solutions describing black holes within various dark matter and dark energy dominated universes, revealing complex horizon dynamics and potential violations of cosmic censorship.

Contribution

It generalizes Lemaitre-Tolman-Bondi solutions to include black holes in different cosmological backgrounds, analyzing horizon behavior and cosmic censorship implications.

Findings

Black hole apparent horizon decreases in DM- or DM+DE-dominated universes

In quintom universes, black hole horizons first shrink then expand

Naked singularity can form when horizons coincide in quintom models

Abstract

We present new exact solutions {which presumably describe} black holes in the background of a spatially flat, pressureless dark matter (DM)-, or dark matter plus dark energy (DM+DE)-, or quintom-dominated universe. These solutions generalize Lemaitre-Tolman-Bondi metrics. For a DM- or (DM+DE)-dominated universe, the area of the black hole apparent horizon (AH) decreases with the expansion of the universe while that of the cosmic AH increases. However, for a quintom-dominated universe, the black hole AH first shrinks and then expands, while the cosmic AH first expands and then shrinks. A (DM+DE)-dominated universe containing a black hole will evolve to the Schwarzschild-de Sitter solution with both AHs approaching constant size. In a quintom-dominated universe, the black hole and cosmic AHs will coincide at a certain time, after which the singularity becomes naked, violating Cosmic Censorship.