{
  "id": "1511.01911",
  "version": "v1",
  "published": "2015-11-05T21:05:43.000Z",
  "updated": "2015-11-05T21:05:43.000Z",
  "title": "The evolution of the equivalent width of the Ha emission line and specific star-formation rate in star-forming galaxies at 1<z<5",
  "authors": [
    "E. Marmol-Queralto",
    "R. J. McLure",
    "F. Cullen",
    "J. S. Dunlop",
    "A. Fontana",
    "D. J. McLeod"
  ],
  "comment": "Submitted to MNRAS, 11 pages, 5 figures, 1 table",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We present the results of a study which uses spectral energy distribution (SED) fitting to investigate the evolution of the equivalent width (EW) of the Halpha emission line in star-forming galaxies over the redshift interval 1<z<5. After first demonstrating the ability of our SED-fitting technique to recover EW(Ha) using a sample of galaxies at z~1.3 with EW(Ha) measurements from 3D-HST grism spectroscopy, we proceed to apply our technique to samples of spectroscopically confirmed and photometric-redshift selected star-forming galaxies at z>=1 in the CANDELS UDS and GOODS-S fields. Confining our analysis to a constant stellar mass range (9.5<log(M/Msun)<10.5), we find that the median EW(Ha) evolves only modestly with redshift, reaching a rest-frame value of EW(Ha)=301+/-30 Angs by redshift z~4.5. Furthermore, using estimates of star-formation rate (SFR) based on both UV luminosity and Ha line flux, we use our galaxy samples to compare the evolution of EW(Ha) and specific star-formation rate (sSFR). Our results indicate that over the redshift range 1<z<5, the evolution displayed by EW(Ha) and sSFR is consistent, and can be adequately parameterized as: propto (1+z)^(1.0+/-0.2). As a consequence, over this redshift range we find that the sSFR and rest-frame EW(Ha) of star-forming galaxies with stellar masses M~10^(10) Msun are related by: EW(Ha)/Ang=(63+/-7)sSFR/Gyr^(-1). Given the current uncertainties in measuring the SFRs of high-redshift galaxies, we conclude that EW(Ha) provides a useful independent tracer of sSFR for star-forming galaxies out to redshifts of z=5.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-11-05T21:05:43.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "specific star-formation rate",
      "star-forming galaxies",
      "ha emission line",
      "equivalent width",
      "redshift range"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015arXiv151101911M",
      "inspire": 1403142
    }
  }
}