{
  "id": "1706.03075",
  "version": "v1",
  "published": "2017-06-09T18:00:06.000Z",
  "updated": "2017-06-09T18:00:06.000Z",
  "title": "[O II] nebular emission from Mg II absorbers: Star formation associated with the absorbing gas",
  "authors": [
    "Ravi Joshi",
    "Raghunathan Srianand",
    "Patrick Petitjean",
    "Pasquier Noterdaeme"
  ],
  "comment": "18 Pages, 18 Figures, 4 Tables (Accepted for the Publication in MNRAS main-journal)",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present nebular emission associated with 198 strong Mg II absorbers at 0.35 $\\le z \\le$ 1.1 in the fibre spectra of quasars from the Sloan Digital Sky Survey. Measured [O II] luminosities (L$_{[O II]}$) are typical of sub-L$^{\\star}$ galaxies with derived star formation rate (uncorrected for fibre losses and dust reddening) in the range of 0.5-20 ${\\rm M_\\odot\\ yr^{-1}}$. Typically less than $\\sim$ 3% of the Mg II systems with rest equivalent width, $W_{2796}$ $\\ge$ 2 \\AA, show L$_{[O II]} \\ge 0.3$ L$^{\\star}_{[O II]}$. The detection rate is found to increase with increasing $W_{2796}$ and $z$. No significant correlation is found between $W_{2796}$ and L$_{[O II]}$ even when we restrict the samples to narrow $z$-ranges. A strong correlation is seen between L$_{[O II]}$ and $z$. While this is expected from the luminosity evolution of galaxies, we show finite fibre size plays a very crucial role in this correlation. The measured nebular line ratios (like [O III]/[O II] and [O III]/H$\\beta$) and their $z$ evolution are consistent with those of galaxies detected in deep surveys. Based on the median stacked spectra, we infer the average metallicity (log Z $\\sim$8.3), ionization parameter (log $q$ $\\sim$7.5) and stellar mass (log (M/M$_\\odot$)$\\sim$9.3). The Mg II systems with nebular emission typically have $W_{2796}$ $\\ge 2$ \\AA, Mg II doublet ratio close to 1 and W(Fe II$\\lambda$2600)/$W_{2796}$ $\\sim 0.5$ as often seen in damped Ly$\\alpha$ and 21-cm absorbers at these redshifts. This is the biggest reported sample of [O II] emission from Mg II absorbers at low impact parameters ideally suited for probing various feedback processes at play in $z\\le 1$ galaxies.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-06-09T18:00:06.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "nebular emission",
      "absorbing gas",
      "sloan digital sky survey",
      "measured nebular line ratios",
      "low impact parameters"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}