Relaxing CMB bounds on Primordial Black Holes: the role of ionization fronts

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Main Authors: Facchinetti, Gaétan, Lucca, Matteo, Clesse, Sébastien
Format: Preprint
Published: 2022
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author Facchinetti, Gaétan
Lucca, Matteo
Clesse, Sébastien
author_facet Facchinetti, Gaétan
Lucca, Matteo
Clesse, Sébastien
contents The accretion of matter onto primordial black holes (PBHs) during the dark ages and the subsequent energy injection in the medium should have left imprints on the cosmic microwave background (CMB) anisotropies. Recent works have claimed stringent CMB limits on the PBH abundance, hardly compatible with a PBH interpretation of the gravitational-wave observations of binary BH mergers. By using a more realistic accretion model based on hydrodynamical simulations and conservative assumptions for the emission efficiency, we show that CMB limits on the PBH abundance are up to two orders of magnitude less stringent than previously estimated between $10$ and $10^4$ M$_\odot$. This reopens the possibility that PBHs might explain at the same time (at least a fraction of) the dark matter, some of the LIGO-Virgo-KAGRA binary BH mergers and the existence of super-massive BHs. More generally, we emphasize that PBH accretion can be a rather complex physical process with velocity dependences that are hard to assess, which introduces large uncertainties in accretion-based limits on the PBH abundance.
format Preprint
id arxiv_https___arxiv_org_abs_2212_07969
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Relaxing CMB bounds on Primordial Black Holes: the role of ionization fronts
Facchinetti, Gaétan
Lucca, Matteo
Clesse, Sébastien
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
The accretion of matter onto primordial black holes (PBHs) during the dark ages and the subsequent energy injection in the medium should have left imprints on the cosmic microwave background (CMB) anisotropies. Recent works have claimed stringent CMB limits on the PBH abundance, hardly compatible with a PBH interpretation of the gravitational-wave observations of binary BH mergers. By using a more realistic accretion model based on hydrodynamical simulations and conservative assumptions for the emission efficiency, we show that CMB limits on the PBH abundance are up to two orders of magnitude less stringent than previously estimated between $10$ and $10^4$ M$_\odot$. This reopens the possibility that PBHs might explain at the same time (at least a fraction of) the dark matter, some of the LIGO-Virgo-KAGRA binary BH mergers and the existence of super-massive BHs. More generally, we emphasize that PBH accretion can be a rather complex physical process with velocity dependences that are hard to assess, which introduces large uncertainties in accretion-based limits on the PBH abundance.
title Relaxing CMB bounds on Primordial Black Holes: the role of ionization fronts
topic Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2212.07969