Evolution of primordial black holes in Jordan-Brans-Dicke cosmology

TL;DR

This paper investigates how primordial black holes evolve within a generalized Jordan-Brans-Dicke cosmological framework, revealing modified evaporation rates, effective radiation accretion, and a mass-dependent survival threshold.

Contribution

It introduces a dynamic scalar field and coupling in Jordan-Brans-Dicke cosmology, analyzing their effects on primordial black hole evolution and survival.

Findings

Black hole evaporation rates are altered compared to standard cosmology.

Radiation accretion can be effective during the radiation era.

A critical initial mass determines black hole survival beyond the present era.

Abstract

We consider the evolution of primordial black holes in a generalyzed Jordan-Brans-Dicke cosmological model where both the Brans-Dicke scalar field and its coupling to gravity are dynamical functions determined from the evolution equations. The evaporation rate for the black holes changes compared to that in standard cosmology. We show that accretion of radiation can proceed effectively in the radiation dominated era. The black hole lifetime shortens for low initial mass, but increases for high initial mass, and is thus considerably modified compared to the case of standard cosmology. We derive a cut-off value for the initial black hole mass, below which primordial black holes evaporate out in the radiation dominated era, and above which they survive beyond the present era.