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Main Authors: Murai, Kai, Sakurai, Kodai, Takahashi, Fuminobu
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.02291
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author Murai, Kai
Sakurai, Kodai
Takahashi, Fuminobu
author_facet Murai, Kai
Sakurai, Kodai
Takahashi, Fuminobu
contents We propose a novel mechanism of primordial black hole (PBH) formation through inverted bubble collapse. In this scenario, bubbles nucleate sparsely in an incomplete first-order phase transition, such that they remain isolated and do not percolate or collide with each other due to the extremely low nucleation rate. This is followed by a bulk phase transition in the rest of the universe that inverts these pre-existing bubbles into false vacuum regions. These spherically symmetric false-vacuum bubbles subsequently collapse to form PBHs. Unlike conventional PBH formation mechanisms associated with domain wall collapse or bubble coalescence, our inverted bubble collapse mechanism naturally ensures spherical collapse. We demonstrate that, when applied to the singlet extension of the Standard Model, this mechanism can produce highly monochromatic PBHs with masses up to ${\cal O}(10^{-7}\,\text{-}\,10^{-5}) M_\odot$, which potentially explain the microlensing events observed in the OGLE and Subaru HSC data.
format Preprint
id arxiv_https___arxiv_org_abs_2502_02291
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Primordial Black Hole Formation via Inverted Bubble Collapse
Murai, Kai
Sakurai, Kodai
Takahashi, Fuminobu
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
We propose a novel mechanism of primordial black hole (PBH) formation through inverted bubble collapse. In this scenario, bubbles nucleate sparsely in an incomplete first-order phase transition, such that they remain isolated and do not percolate or collide with each other due to the extremely low nucleation rate. This is followed by a bulk phase transition in the rest of the universe that inverts these pre-existing bubbles into false vacuum regions. These spherically symmetric false-vacuum bubbles subsequently collapse to form PBHs. Unlike conventional PBH formation mechanisms associated with domain wall collapse or bubble coalescence, our inverted bubble collapse mechanism naturally ensures spherical collapse. We demonstrate that, when applied to the singlet extension of the Standard Model, this mechanism can produce highly monochromatic PBHs with masses up to ${\cal O}(10^{-7}\,\text{-}\,10^{-5}) M_\odot$, which potentially explain the microlensing events observed in the OGLE and Subaru HSC data.
title Primordial Black Hole Formation via Inverted Bubble Collapse
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2502.02291