Open Questions on the Future of Primordial Black Holes

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29 Aug 2024

Authors:

(1) Antonio Riotto, Département de Physique Theorique, Universite de Geneve, 24 quai Ansermet, CH-1211 Geneve 4, Switzerland and Gravitational Wave Science Center (GWSC), Universite de Geneve, CH-1211 Geneva, Switzerland;

(2) Joe Silk, Institut d’Astrophysique, UMR 7095 CNRS, Sorbonne Universite, 98bis Bd Arago, 75014 Paris, France, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore MD 21218, USA, and Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH, UK.

Abstract and 1 Introduction

2 Some open questions

2.1 What is the abundance of PBHs?

2.2 What is the effect of PBH clustering?

2.3 What fraction of the currently observed GW events can be ascribed to PBHs?

2.4 Are PBHs the Dark Matter?

3 The PBH Roadmap

3.1 High redshift mergers

3.2 Sub-solar PBHs

3.3 Plugging the pair instability gap with PBH?

3.4 PBH eccentricity, 3.5 PBH spin and 3.6 Future gamma-ray telescopes

4 Conclusions and References

2 Some open questions

How well do we know the PBH abundance? And over what mass range? How well can we ascertain the PBH clustering properties and therefore the GW signal from binary mergers via LIGO and future terrestrial GW interferometers? And can we use the vicinities of SMBH amd IMBH, most likely rich in dark matter and where PBH abundances are in consequence likely to be enhanced, as potential sources of EMRI signals for experiments such as LISA? We briefly discuss such open theoretical and observational questions below.

This paper is available on arxiv under CC BY 4.0 DEED license.