Accretion of nonminimally coupled scalar fields into black holes

TL;DR

This paper investigates how nonminimally coupled scalar fields influence black hole mass evolution, revealing unique behaviors such as mass decrease for small black holes, with implications for cosmology and black hole observations.

Contribution

It provides an analytical solution for black hole mass evolution with nonminimal scalar coupling, highlighting behaviors distinct from minimal coupling cases.

Findings

Scalar field accretion can decrease black hole mass for small black holes.

Mass evolution differs qualitatively from minimal coupling scenarios.

Observational data can constrain nonminimally coupled energy content.

Abstract

By using a quasi-stationary approach, we consider the mass evolution of Schwarzschild black holes in the presence of a nonminimally coupled cosmological scalar field. The mass evolution equation is analytically solved for generic coupling, revealing a qualitatively distinct behavior from the minimal coupling case. In particular, for black hole masses smaller than a certain critical value, the accretion of the scalar field can lead to mass decreasing even if no phantom energy is involved. The physical validity of the adopted quasi-stationary approach and some implications of our result for the evolution of primordial and astrophysical black holes are discussed. More precisely, we argue that black hole observational data could be used to place constraints on the nonminimally coupled energy content of the universe.