Evolution of Primordial Black Hole Mass Spectrum in Brans-Dicke Theory

TL;DR

This paper studies how primordial black holes evolve in Brans-Dicke cosmology, considering radiation accretion and Hawking evaporation, and examines their impact on universe expansion and stability of black hole energy density.

Contribution

It provides analytic solutions for black hole energy density in equilibrium with radiation within Brans-Dicke theory, highlighting the effects of accretion and evaporation on stability and evolution.

Findings

Equilibrium solutions act as attractors, ensuring system stability.

Radiation accretion delays equilibrium onset across eras.

Inclusion of accretion influences the timing of black hole-radiation equilibrium.

Abstract

We investigate the evolution of primordial black hole mass spectrum by including both accretion of radiation and Hawking evaporation within Brans-Dicke cosmology in radiation, matter and vacuum-dominated eras. We also consider the effect of evaporation of primordial black holes on the expansion dynamics of the universe. The analytic solutions describing the energy density of the black holes in equilibrium with radiation are presented. We demonstrate that these solutions act as attractors for the system ensuring stability for both linear and nonlinear situations. We show, however, that inclusion of accretion of radiation delays the onset of this equilibrium in all radiation, matter and vacuum-dominated eras.