{
  "abstract": "Localized fast radio bursts (FRBs) show substantial scatter in dispersion measure (DM) about the mean cosmic DM--redshift relation, also known as the Macquart relation. Both foreground structure and host galaxies contribute to this scatter. In this work, we examine foreground tracers and host galaxy properties using a parent catalog of 136 localized FRBs with measured DMs and spectroscopic host redshifts. Among 77 FRBs within the Gfinder footprint, DM excess relative to a fixed Macquart mean increases with foreground group count excess, with a Spearman coefficient of 0.459. Adding the foreground term to a mean host baseline reduces the leave-one-out root mean square error (RMSE) and mean absolute error (MAE) in extragalactic DM by \\(13.0\\%\\) and \\(7.5\\%\\), respectively. For 20 of these FRBs with optical host axis ratio measurements, adding a foreground term calibrated on the other 57 FRBs to the host shape model reduces the observer-frame leave-one-out RMSE from \\(76.3\\) to \\(64.0~\\mathrm{pc\\,cm^{-3}}\\) and MAE from \\(54.2\\) to \\(50.2~\\mathrm{pc\\,cm^{-3}}\\). And the in-sample residual standard deviation in the host rest frame decreases by \\(20.2\\%\\). Idealized galaxy models based on the Milky Way electron density distribution produce DM changes with inclination comparable to the fitted amplitude under the adopted assumptions.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.23333",
  "author_total": 2,
  "authors": [
    {
      "name": "Jiale Wang"
    },
    {
      "name": "Taotao Fang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/350230z0qf38c.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.23333",
  "fulltext_url": null,
  "id": "350230z0qf38c",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.23333",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "openalex",
      "3103|Gamma-ray bursts and supernovae"
    ]
  ],
  "openalex": "W7222968223",
  "pdf_url": "https://arxiv.org/pdf/2610.23333",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/350230z0qf38c.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:30:32Z",
      "native_id": "2610.23333",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.23333"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    }
  ],
  "title": "Foreground Groups and Host-Galaxy Geometry in the Dispersion-Measure Scatter of Fast Radio Bursts",
  "title_text": "Foreground Groups and Host-Galaxy Geometry in the Dispersion-Measure Scatter of Fast Radio Bursts",
  "type": "preprint",
  "updated_at": "2026-10-30T12:33:28Z",
  "url": "https://research.draconitic.com/paper/350230z0qf38c",
  "venue": "arXiv",
  "versions": []
}