{
  "id": "1605.09742",
  "version": "v1",
  "published": "2016-05-31T17:55:27.000Z",
  "updated": "2016-05-31T17:55:27.000Z",
  "title": "Constraint on a cosmological variation in the proton-to-electron mass ratio from electronic CO absorption",
  "authors": [
    "M. Daprà",
    "M. L. Niu",
    "E. J. Salumbides",
    "M. T. Murphy",
    "W. Ubachs"
  ],
  "comment": "44 pages, 9 figures, accepted for publication in the Astrophysical Journal",
  "categories": [
    "astro-ph.CO",
    "astro-ph.GA"
  ],
  "abstract": "Carbon monoxide (CO) absorption in the sub-damped Lyman-$\\alpha$ absorber at redshift $z_{abs} \\simeq 2.69$, toward the background quasar SDSS J123714.60+064759.5 (J1237+0647), was investigated for the first time in order to search for a possible variation of the proton-to-electron mass ratio, $\\mu$, over a cosmological time-scale. The observations were performed with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 40 per 2.5 kms$^{-1}$ per pixel at $\\sim 5000$ \\AA. Thirteen CO vibrational bands in this absorber are detected: the A$^{1}\\Pi$ - X$^{1}\\Sigma^{+}$ ($\\nu'$,0) for $\\nu' = 0 - 8$, B$^{1}\\Sigma^{+}$ - X$^{1}\\Sigma^{+}$ (0,0), C$^{1}\\Sigma^{+}$ - X$^{1}\\Sigma^{+}$ (0,0), and E$^{1}\\Pi$ - X$^{1}\\Sigma^{+}$ (0,0) singlet-singlet bands and the d$^{3}\\Delta$ - X$^{1}\\Sigma^{+}$ (5,0) singlet-triplet band. An updated database including the most precise molecular inputs needed for a $\\mu$-variation analysis is presented for rotational levels $J = 0 - 5$, consisting of transition wavelengths, oscillator strengths, natural lifetime damping parameters, and sensitivity coefficients to a variation of the proton-to-electron mass ratio. A comprehensive fitting method was used to fit all the CO bands at once and an independent constraint of $\\Delta\\mu/\\mu = (0.7 \\pm 1.6_{stat} \\pm 0.5_{syst}) \\times 10^{-5}$ was derived from CO only. A combined analysis using both molecular hydrogen and CO in the same J1237+0647 absorber returned a final constraint on the relative variation of $\\Delta\\mu/\\mu = (-5.6 \\pm 5.6_{stat} \\pm 3.1_{syst}) \\times 10^{-6}$, which is consistent with no variation over a look-back time of $\\sim 11.4$ Gyrs.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-05-31T17:55:27.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "proton-to-electron mass ratio",
      "cosmological variation",
      "constraint",
      "absorption",
      "electronic"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 44,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}