{
  "id": "1709.03503",
  "version": "v1",
  "published": "2017-09-11T18:00:00.000Z",
  "updated": "2017-09-11T18:00:00.000Z",
  "title": "The ionization properties of extreme nearby star-forming regions",
  "authors": [
    "Jacopo Chevallard",
    "Stéphane Charlot",
    "Peter Senchyna",
    "Daniel P. Stark",
    "Alba Vidal-García",
    "Anna Feltre",
    "Julia Gutkin",
    "Tucker Jones",
    "Ramesh Mainali",
    "Aida Wofford"
  ],
  "comment": "6 pages, 5 figures, submitted to MNRAS Letters, comments welcome",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "The bulk of hydrogen-ionizing photons necessary to reionize the intergalactic medium (IGM) by redshift z~6 is likely to have arisen from stars in low-mass galaxies. Whether these galaxies were numerous enough at z>6 to reionize the IGM entirely depends on their production rate of H-ionizing photons, xi_ion, and the fraction of these escaping into the IGM. We derive a novel diagnostic of xi_ion based on the equivalent width of the bright [OIII]4959,5007 line doublet, which does not require measurements of H-recombination lines. We calibrate this diagnostic through the analysis of the luminosities of 15 nebular emission lines in high-quality optical spectra of 10 low-redshift analogs of primeval galaxies, using the new-generation spectral analysis tool Beagle. The success of this analysis confirms the ability of the models to constrain the ionized-gas properties of extreme star-forming regions, paving the way to similar analyses at high redshift. The new xi_ion diagnostic can be used to derive more accurate estimates of this parameter than currently possible from the contamination by Hbeta+[OIII]4959,5007 of broad-band photometry in distant galaxies, and, in the future, from direct observations of [OIII]4959,5007 out to z~9.5 using JWST/NIRSpec.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-09-11T18:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "extreme nearby star-forming regions",
      "ionization properties",
      "new-generation spectral analysis tool beagle",
      "nebular emission lines"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}