{
  "abstract": "We investigate primordial black hole (PBH) formation from primordial magnetic fields generated during a non-singular ekpyrotic bounce. A time-dependent coupling between the electromagnetic field and a scalar background breaks conformal invariance and amplifies gauge field fluctuations during contraction, generating magnetic fields whose anisotropic stress dominates during radiation domination. By retaining finite-wavenumber cutoffs, we compute the ultraviolet-dominated curvature spectrum, evaluate density-perturbation variance, and determine PBH abundances using both monochromatic and critical-collapse prescriptions. For benchmark parameters, the critical collapse mass spectrum peaks at $M\\simeq 2.0\\times10^{-3}M_\\odot$ , with a total PBH dark matter fraction of $f_{PBH}\\approx 10^{-5}$, forming a subdominant subsolar PBH population. Enforcing the cosmological overclosure bound ($f_{\\mathrm{PBH}} \\le 1$) constrains the primary background parameters, namely the end-of-contraction Hubble scale ($H_{\\mathrm{end}} \\le 1.6 \\times 10^3~\\mathrm{GeV}$) and the contraction exponent ($q \\le 0.247$), establishing a physical boundary consistent with the electromagnetic backreaction limit. Shifting to asteroid-mass PBHs or a larger dark matter fraction requires modifying the ultraviolet cutoff and contraction duration. This analysis highlights the essential role of finite-wavenumber cutoffs and assumed-collapse prescriptions in linking bounce magnetogenesis to the predicted PBH abundance.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.21658",
  "author_total": 2,
  "authors": [
    {
      "name": "Ajeet Singhal"
    },
    {
      "name": "Shreya Banerjee"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8bn8nky8pmmsd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.21658",
  "fulltext_url": null,
  "id": "8bn8nky8pmmsd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.21658",
  "language": null,
  "licence": "CC0-1.0",
  "licence_label": "CC0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/publicdomain/zero/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7222561138",
  "pdf_url": "https://arxiv.org/pdf/2610.21658",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8bn8nky8pmmsd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:50Z",
      "native_id": "2610.21658",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.21658"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    }
  ],
  "title": "From Cosmic Bounces to Primordial Black Holes: The Role of Primordial Magnetic Fields",
  "title_text": "From Cosmic Bounces to Primordial Black Holes: The Role of Primordial Magnetic Fields",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:50Z",
  "url": "https://research.draconitic.com/paper/8bn8nky8pmmsd",
  "venue": "arXiv",
  "versions": []
}