{
  "id": "1601.07909",
  "version": "v1",
  "published": "2016-01-28T21:00:42.000Z",
  "updated": "2016-01-28T21:00:42.000Z",
  "title": "The gas mass of star-forming galaxies at $z \\approx 1.3$",
  "authors": [
    "Nissim Kanekar",
    "Shiv Sethi",
    "K. S. Dwarakanath"
  ],
  "comment": "5 pages, 3 figures, accepted for publication in Astrophysical Journal Letters",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We report a Giant Metrewave Radio Telescope (GMRT) search for HI 21cm emission from a large sample of star-forming galaxies at $z \\approx 1.18 - 1.34$, lying in sub-fields of the DEEP2 Redshift Survey. The search was carried out by co-adding (\"stacking\") the HI 21cm emission spectra of 857 galaxies, after shifting each galaxy's HI 21cm spectrum to its rest frame. We obtain the $3\\sigma$ upper limit S$_{\\rm{HI}} < 2.5 \\mu$Jy on the average HI 21cm flux density of the 857 galaxies, at a velocity resolution of $\\approx 315$ km s$^{-1}$. This yields the $3\\sigma$ constraint M$_{\\rm{HI}} < 2.1 \\times 10^{10} \\times \\left[\\Delta {\\rm V}/315 \\rm{km/s} \\right]^{1/2} \\textrm{M}_\\odot$ on the average HI mass of the 857 stacked galaxies, the first direct constraint on the atomic gas mass of galaxies at $z > 1$. The implied limit on the average atomic gas mass fraction (relative to stars) is ${\\rm M}_{\\rm GAS}/{\\rm M}_* < 0.5$, comparable to the cold molecular gas mass fraction in similar star-forming galaxies at these redshifts. We find that the cosmological mass density of neutral atomic gas in star-forming galaxies at $z \\approx 1.3$ is $\\Omega_{\\rm GAS} < 3.7 \\times 10^{-4}$, significantly lower than $\\Omega_{\\rm GAS}$ estimates in both galaxies in the local Universe and damped Lyman-$\\alpha$ absorbers at $z \\geq 2.2$. Blue star-forming galaxies thus do not appear to dominate the neutral atomic gas content of the Universe at $z \\approx 1.3$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-01-28T21:00:42.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "star-forming galaxies",
      "neutral atomic gas",
      "hi 21cm emission",
      "cold molecular gas mass fraction",
      "average hi 21cm flux density"
    ],
    "publication": {
      "doi": "10.3847/2041-8205/818/2/L28"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1418457
    }
  }
}