{
  "id": "1605.07186",
  "version": "v1",
  "published": "2016-05-23T20:00:08.000Z",
  "updated": "2016-05-23T20:00:08.000Z",
  "title": "Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies",
  "authors": [
    "C. C. Steidel",
    "A. L. Strom",
    "M. Pettini",
    "G. C. Rudie",
    "N. A. Reddy",
    "R. F. Trainor"
  ],
  "comment": "29 pages, 17 figures. Accepted for publication in the Astrophysical Journal",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We present a combined analysis of rest-frame far-UV (1000-2000 A) and rest-frame optical (3600-7000 A) composite spectra formed from very deep observations of a sample of 30 star-forming galaxies with z=2.4+/-0.1, selected to be representative of the full KBSS-MOSFIRE spectroscopic survey. Since the same massive stars are responsible for the observed FUV continuum and the excitation of the observed nebular emission, a self-consistent stellar population synthesis model must simultaneously match the details of the far-UV stellar+nebular continuum and-- when inserted as the excitation source in photoionization models-- account for all observed nebular emission line ratios. We find that only models including massive star binaries, having low stellar metallicity (Z_*/Z_{sun} ~ 0.1) but relatively high ionized gas-phase oxygen abundances (Z_{neb}/Z_{sun} ~ 0.5), can successfully match all of the observational constraints. We argue that this apparent discrepancy is naturally explained by highly super-solar O/Fe [4-5 times (O/Fe)_{sun}], expected for gas whose enrichment is dominated by the products of core-collapse supernovae. Once the correct ionizing spectrum is identified, photoionization models reproduce all of the observed strong emission line ratios, the direct T_e measurement of O/H, and allow accurate measurement of the gas-phase abundance ratios of N/O and C/O -- both of which are significantly sub-solar but, as for O/Fe, are in remarkable agreement with abundance patterns observed in Galactic thick disk, bulge, and halo stars with similar O/H. High nebular excitation is the rule at high-z (and rare at low-z) because of systematically shorter enrichment timescales (<<1 Gyr): low Fe/O environments produce harder (and longer-lived) stellar EUV spectra at a given O/H, enhanced by dramatic effects on the evolution of massive star binaries.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-05-23T20:00:08.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high redshift galaxies",
      "nebular spectra",
      "fe/o environments produce harder",
      "stellar population synthesis model",
      "high ionized gas-phase oxygen"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 29,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1465475
    }
  }
}