{
  "id": "2011.12296",
  "version": "v1",
  "published": "2020-11-24T19:00:00.000Z",
  "updated": "2020-11-24T19:00:00.000Z",
  "title": "Modelling the Statistics of Cold Neutral Medium in Absorption-selected High-redshift Galaxies",
  "authors": [
    "Jens-Kristian Krogager",
    "Pasquier Noterdaeme"
  ],
  "comment": "A&A Letter, Accepted for publication, 5 pages (incl. 2 page auxiliary data table)",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present a statistical model of the selection function of cold neutral gas in high-redshift (z~2.5) absorption systems. The model is based on the canonical two-phase model of the neutral gas in the interstellar medium and contains only one parameter for which we do not have direct observational priors: namely the central pressure (P*) of an L* halo at z=2.5. Using observations of the fraction of cold gas absorption in strong HI-selected absorbers, we are able to constrain P*. The model simultaneously reproduces the column density distributions of HI and H$_2$, and we derive an expected total incidence of cold gas at z~2.5 of $l_{CNM} = 12\\times 10^{-3}$. Compared to recent measurements of the incidence of CI-selected absorbers (EW$_{CI\\,1560}$ > 0.4 \\r{A}), the value of $l_{CNM}$ from our model indicates that only ~15% of the total cold gas would lead to strong CI absorption (EW > 0.4 \\r{A}). Nevertheless, CI lines are extremely useful probes of the cold gas as they are relatively easy to detect and provide direct constraints on the physical conditions. Lastly, our model self-consistently reproduces the fraction of cold gas absorbers as a function of N(HI).",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-11-24T19:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "cold neutral medium",
      "absorption-selected high-redshift galaxies",
      "statistics",
      "strong ci absorption",
      "direct observational priors"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}