{
  "abstract": "Characterizing the hot (T ~ 10$^{6}$ K) circumgalactic medium (CGM) around Milky Way-mass (MW-mass) galaxies is critical to a full understanding of galaxy evolution. In this second paper of the \"X-rays in Romulus25\" series, we unpack the specific physical processes giving rise to the presence of hot X-ray emitting gas in the halos of galaxies from the Romulus25 (R25) simulation, focusing on L$_{*}$ galaxies. We determine that a strong correlation appears between the mass of hot CGM gas, M$_{gas, T > 10^{5.5} K}$, and the X-ray emissivity, $ε_χ$, measured in the first paper of this series, (Sanchez et al. 2026a, submitted). There is also a secondary correlation between M$_{gas, T > 10^{5.5} K}$ and $ε_χ$ with the average metallicity of the hot CGM gas, $\\bar{Z}_{gas, T > 10^{5.5} K}$. We use the well-studied PIONEER simulations from Sanchez et al. (2019), a set of zoom-in MW-mass galaxies run with the genetic modification technique of Roth et al. (2016) and the same physics as R25, to interpret these correlations. We determine that the presence of hot X-ray emitting gas is determined by two key processes: 1) the quantity of hot gas mass in the CGM, M$_{gas, T > 10^{5.5} K}$, is set by the combined total energy injection of $both$ stellar and AGN feedback, and 2) together the average temperature and metallicity of the hot CGM changes the soft X-ray spectrum of the gas resulting in brighter metal-rich CGM and dimmer metal-poor CGM for the same quantity of M$_{gas, T > 10^{5.5} K}$. These results indicate, for the first time, that metal-rich gas halos may bias X-ray observations of MW-mass galaxies.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.37769",
  "author_total": 7,
  "authors": [
    {
      "name": "N. Nicole Sanchez"
    },
    {
      "name": "Andrew Benson"
    },
    {
      "name": "Gwen Rudie"
    },
    {
      "name": "Ben Oppenheimer"
    },
    {
      "name": "Hannah Bish"
    },
    {
      "name": "John ZuHone"
    },
    {
      "name": "Michael Tremmel"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/44v774m3qsxvq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.37769",
  "fulltext_url": null,
  "id": "44v774m3qsxvq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.37769",
  "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": null,
  "pdf_url": "https://arxiv.org/pdf/2610.37769",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/44v774m3qsxvq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:23Z",
      "native_id": "2610.37769",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.37769"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Extra! Extra! X-ray Emission!: X-rays in Romulus25, Part II - Physical Drivers of X-ray Emission in the CGM",
  "title_text": "Extra! Extra! X-ray Emission!: X-rays in Romulus25, Part II - Physical Drivers of X-ray Emission in the CGM",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/44v774m3qsxvq",
  "venue": "arXiv",
  "versions": []
}