Accretion of Generalized Chaplygin Gas onto Cosmologically Coupled Black Holes

TL;DR

This paper investigates how the Generalized Chaplygin Gas, a dark fluid driving cosmic acceleration, accretes onto black holes within an expanding universe, analyzing horizon evolution in different cosmological eras.

Contribution

It introduces a perturbative method to study black hole mass evolution due to GCG accretion using the McVittie metric in cosmological backgrounds.

Findings

Analytical expressions for black hole and horizon evolution during matter and de Sitter eras.

Accretion onset time depends on the amount of matter available for accretion.

In matter-dominated era, more matter delays the start of accretion.

Abstract

We study the accretion of cosmic dark fluids, responsible for driving the accelerated expansion of the universe, onto cosmologically coupled black holes. More specifically, we focus on the accretion of the Generalized Chaplygin Gas (GCG). To incorporate the global features of the GCG into this analysis, we employ the McVittie metric, which describes a black hole embedded in an expanding cosmological background. Within this framework, accretion is studied while consistently accounting for the backreaction on the metric components. Using a perturbative approach, we derive an expression for the effective black hole mass and for the evolution of both the black hole and cosmological apparent horizons under accretion. The analysis is performed in two distinct cosmological regimes: first, a matter-dominated era, and subsequently, a de Sitter era. In both cases, it is possible to determine analytically the instant in which accretion begins. For the matter-dominated era, the analytical expression shows that the greater the amount of matter available for accretion, the longer the accretion takes to start.