Primordial Black Holes without fine-tuning from a light stochastic spectator field

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Hauptverfasser: Stamou, Ioanna, Clesse, Sebastien
Format: Preprint
Veröffentlicht: 2023
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author Stamou, Ioanna
Clesse, Sebastien
author_facet Stamou, Ioanna
Clesse, Sebastien
contents We investigate a mechanism of primordial black hole (PBH) formation that avoids any dependence on specific inflationary features or exotic physics. In this scenario, the required large curvature fluctuations leading to PBH formation are generated after inflation by the quantum fluctuations of a light stochastic spectator field during inflation, when this field transiently dominates the energy density. We calculate the dynamics of such a spectator field during and after inflation, the distribution of induced curvature perturbations and their non-Gaussian tails leading to the copious production of PBHs. For a plateau-like potential, this scenario produces an extended PBH mass distribution with a peak at the solar-mass scale when one takes into account the effects of the thermal history. What is remarkable in this scenario is the absence of parameter fine-tuning. Instead, it invokes an anthropic selection over all the realizations of PBH abundances predicted by the field stochasticity. This scenario offers a novel perspective for the formation of PBHs with minimal ingredients and without the need of fine-tuning. It is amenable to observational tests, notably with the gravitational-wave observations of black hole mergers and of a background at nanoHertz frequency, as recently observed by pulsar timing arrays.
format Preprint
id arxiv_https___arxiv_org_abs_2310_04174
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Primordial Black Holes without fine-tuning from a light stochastic spectator field
Stamou, Ioanna
Clesse, Sebastien
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We investigate a mechanism of primordial black hole (PBH) formation that avoids any dependence on specific inflationary features or exotic physics. In this scenario, the required large curvature fluctuations leading to PBH formation are generated after inflation by the quantum fluctuations of a light stochastic spectator field during inflation, when this field transiently dominates the energy density. We calculate the dynamics of such a spectator field during and after inflation, the distribution of induced curvature perturbations and their non-Gaussian tails leading to the copious production of PBHs. For a plateau-like potential, this scenario produces an extended PBH mass distribution with a peak at the solar-mass scale when one takes into account the effects of the thermal history. What is remarkable in this scenario is the absence of parameter fine-tuning. Instead, it invokes an anthropic selection over all the realizations of PBH abundances predicted by the field stochasticity. This scenario offers a novel perspective for the formation of PBHs with minimal ingredients and without the need of fine-tuning. It is amenable to observational tests, notably with the gravitational-wave observations of black hole mergers and of a background at nanoHertz frequency, as recently observed by pulsar timing arrays.
title Primordial Black Holes without fine-tuning from a light stochastic spectator field
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2310.04174