{
  "abstract": "For over two decades, Na I D ($λ\\lambda5891.58, 5897.56$ Å) absorption has been the primary optical tracer of cool, neutral gas in galaxies. In contrast, Ca II H&K ($λλ$3934.78, 3969.59 Å), which traces both neutral and ionized gas, has been comparatively unexplored. Here, we present a comparative study of the Na I D and Ca II H&K interstellar absorption lines using spatially resolved MaNGA IFU spectroscopy of 140 red geyser galaxies (local quiescent systems hosting low-luminosity AGN with bisymmetric ionized outflows) and a control sample of 140 quiescent galaxies. Using Gaussian fits to the Na I D and Ca II K lines, we measure gas velocity and dispersion. We find that the Ca II reservoirs are up to ~ 6 times larger in area, twice as radially extended, and have ~ 1.7 - 1.8x broader line widths than Na I D. Furthermore, Na I D shows a direct dependence on dust reservoir size, but the correlation vanishes for Ca II. In only ~ 20% of galaxies do the Na I D detections extend beyond dust regions, but this fraction jumps to ~70% for Ca II. Using these findings, we argue that dust plays a significant role in shielding Na I D from ionizing radiation, whereas Ca II, with its higher ionization potential, is not as dependent on shielding and can more easily survive beyond regions of dust. Na I D and Ca II trace distinct gas components, and studying both together provides a more complete picture of gas flows in galaxies.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.23288",
  "author_total": 6,
  "authors": [
    {
      "name": "Arian Moghni"
    },
    {
      "name": "Timothy M. Heckman"
    },
    {
      "name": "Namrata Roy"
    },
    {
      "name": "Kyle B. Westfall"
    },
    {
      "name": "Kevin Bundy"
    },
    {
      "name": "Kate H. R. Rubin"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6beaqan1a6h08.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.23288",
  "fulltext_url": null,
  "id": "6beaqan1a6h08",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.23288",
  "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": "W7214007673",
  "pdf_url": "https://arxiv.org/pdf/2609.23288",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6beaqan1a6h08.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.23288",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.23288"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Tracing Interstellar Gas in Quiescent Galaxies Using Na I D and Ca II H&K Absorption",
  "title_text": "Tracing Interstellar Gas in Quiescent Galaxies Using Na I D and Ca II H&K Absorption",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/6beaqan1a6h08",
  "venue": "arXiv",
  "versions": []
}