Cosmological quintessence accretion onto primordial black holes : conditions for their growth to the supermassive scale

TL;DR

This paper investigates the feasibility of primordial black holes growing into supermassive black holes through accretion of quintessence and radiation, finding significant challenges and fine-tuning requirements for such growth.

Contribution

It provides analytical solutions and detailed analysis of black hole growth in a quintessence-dominated universe, highlighting the difficulties and constraints involved.

Findings

Growth timescale exceeds the Hubble time.

Required quintessence density exceeds unity.

Quenching of black hole growth due to background evolution.

Abstract

In this work we revisit the growth of small primordial black holes (PBHs) immersed in a quintessential field and/or radiation to the supermassive black hole (SMBHs) scale. We show the difficulties of scenarios in which such huge growth is possible. For that purpose we evaluated analytical solutions of the differential equations (describing mass evolution) and point out the strong fine tuning for that conclusions. The timescale for growth in a model with a constant quintessence flux is calculated and we show that it is much bigger than the Hubble time.The fractional gain of the mass is further evaluated in other forms, including quintessence and/or radiation. We calculate the cosmological density $\Omega$ due to quintessence necessary to grow BHs to the supermassive range and show it to be much bigger than one. We also describe the set of complete equations analyzing the evolution of the BH+quintessence universe, showing some interesting effects such the quenching of the BH mass growth due to the evolution of the background energy. Additional constraints obtained by using the Holographic Bound are also described. The general equilibrium conditions for evaporating/accreting black holes evolving in a quintessence/radiation universe are discussed in the Appendix.