{
  "abstract": "Over the last decade, magnetic fields (B-fields) have become a common ingredient in galaxy formation simulations. Although seemingly unimportant in matching observational constraints such as the $M_*-M_{\\rm halo}$ relations, the B-field influences the circumgalactic medium (CGM) gas and determines cosmic ray (CR) propagation, making it an indispensable non-thermal component. Nevertheless, the intricate physics of B-fields, particularly how they evolve to the observed $μ$G-level field, remains largely elusive. In this work, we systematically address the evolution of B-fields over cosmic time using the FIRE-2 (Feedback In Realistic Environments) magnetohydrodynamics (MHD) simulations. We present results for both Milky Way (MW)-mass and dwarf galaxies, with and without CRs. We find that CRs have little impact on B-field properties, while the halo mass controls the saturated B-field strength at $z\\sim 0$. However, all runs reach a halo-independent magnetic-to-turbulent ratio of $f_{\\rm B}\\sim 1-10\\%$, though the methods used to measure turbulence could affect this value. We identify a three-stage evolutionary course for the B-field in tandem with galaxy formation: i. expansion, ii. amplification, and iii. saturation. The feature is universal, though the timings depend on the initial location and star formation history of the gas. Flux-freezing is the predominant driver for the first and last stages, exhibiting power relations $B\\sim ρ^{2/3}$ and $ρ^{1/2}$, although the latter could also be explained by dynamical and energetic equilibria. The intermediate amplification stage, potentially driven by ``dynamos'', is fuelled by structure formation, feedback, and gas turbulence. We conjecture a numerically triggered, turbulence-driven amplification process to explain this phenomenon.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.17216",
  "author_total": 4,
  "authors": [
    {
      "name": "Yue Samuel Lu"
    },
    {
      "name": "Dušan Kereš"
    },
    {
      "name": "Philip F. Hopkins"
    },
    {
      "name": "Sam B. Ponnada"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4g2kpd85bnfq1.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.17216",
  "fulltext_url": null,
  "id": "4g2kpd85bnfq1",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.17216",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7221763571",
  "pdf_url": "https://arxiv.org/pdf/2610.17216",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-12",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4g2kpd85bnfq1.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:06Z",
      "native_id": "2610.17216",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.17216"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Magnetic field evolution in feedback-dominated galaxies",
  "title_text": "Magnetic field evolution in feedback-dominated galaxies",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:06Z",
  "url": "https://research.draconitic.com/paper/4g2kpd85bnfq1",
  "venue": "arXiv",
  "versions": []
}