Dynamical model for primordial black holes

TL;DR

This paper develops a dynamical model for primordial black holes using the extended McVittie spacetime, analyzing their mass evolution based on initial conditions and cosmological factors, and exploring the formation of supermassive black holes.

Contribution

It introduces a new dynamical framework for primordial black hole evolution that accounts for initial seed mass, emergence time, and dark matter velocities, extending previous static models.

Findings

Black hole mass evolution depends on initial seed mass and dark matter velocities.

A wide range of primordial black hole masses, including supermassive ones, can form from small seeds.

The McVittie model aligns with Schwarzschild when neglecting other astrophysical processes.

Abstract

Primordial black holes are analytically and numerically discussed based on the extended McVittie spacetime solution. By assuming that dark matter and radiation are the only sources of energy accreted by the forming central object, it is found that the black-hole mass evolution depends on the initial mass of the seed, the time in which the black hole emerges, and also on the average peculiar velocity of dark matter particles. Constraints on the initial conditions of the primordial black holes are derived from profiles of the black-hole accretion mechanism and cosmological environment. A large range of masses is compatible with our approach. In particular, masses of the order of $10^{10}M_{\odot}$ today may also be generated from small seeds. An incubation time for the emerging horizons is observed when the initial masses of the seeds are close to the particle-horizon mass. It is also argued that the McVittie-type description is consistent with the Schwarzschild solution as long as other astrophysical processes near the central object are neglected.