{
  "id": "2306.03916",
  "version": "v1",
  "published": "2023-06-06T18:00:01.000Z",
  "updated": "2023-06-06T18:00:01.000Z",
  "title": "Connecting the escape fraction of Lyman-alpha and Lyman-continuum photons in star-forming galaxies at $\\mathbf{z\\simeq 4-5}$",
  "authors": [
    "R. Begley",
    "F. Cullen",
    "R. J. McLure",
    "A. E. Shapley",
    "J. S. Dunlop",
    "A. C. Carnall",
    "D. J. McLeod",
    "C. T. Donnan",
    "M. L. Hamadouche",
    "T. M. Stanton"
  ],
  "comment": "12 pages, 7 figures, MNRAS submitted",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "We present a study of the connection between the escape fraction of Lyman-alpha (Ly$\\alpha$) and Lyman-continuum (LyC) photons within a sample of N=152 star-forming galaxies selected from the VANDELS survey at $3.85<z_{spec}<4.95$. By combining measurements of H$\\alpha$ equivalent width $(W_\\lambda(\\rm{H\\alpha}))$ derived from broad-band photometry with Ly$\\alpha$ equivalent width $(W_\\lambda(Ly\\alpha))$ measurements from VANDELS spectra, we individually estimate $f_{\\rm{esc}}^{Ly\\alpha}$ for our full sample. In agreement with previous studies, we find a positive correlation between $W_\\lambda(Ly\\alpha)$ and $f_{\\rm{esc}}^{Ly\\alpha}$, increasing from $f_{\\rm{esc}}^{Ly\\alpha}\\simeq0.04$ at $W_\\lambda(Ly\\alpha)=10$\\r{A} to $f_{\\rm{esc}}^{Ly\\alpha}\\simeq0.1$ at $W_\\lambda(Ly\\alpha)=25$\\r{A}. For the first time at $z\\sim4-5$, we investigate the relationship between $f_{\\rm{esc}}^{Ly\\alpha}$ and $f_{\\rm{esc}}^{\\rm{LyC}}$ using $f_{\\rm{esc}}^{\\rm{LyC}}$ estimates derived using the equivalent widths of low-ionization, FUV absorption lines in composite VANDELS spectra. Our results indicate that $f_{\\rm{esc}}^{\\rm{LyC}}$ rises monotonically with $f_{\\rm{esc}}^{Ly\\alpha}$, following a relation of the form $f_{\\rm{esc}}^{\\rm{LyC}}\\simeq 0.15 f_{\\rm{esc}}^{Ly\\alpha}$. Based on composite spectra of sub-samples with roughly constant $W_\\lambda(Ly\\alpha)$, but very different $f_{\\rm{esc}}^{Ly\\alpha}$, we show that the $f_{\\rm{esc}}^{\\rm{LyC}}-f_{\\rm{esc}}^{Ly\\alpha}$ correlation is not driven by a secondary correlation between $f_{\\rm{esc}}^{Ly\\alpha}$and $W_\\lambda(Ly\\alpha)$. The $f_{\\rm{esc}}^{\\rm{LyC}}-f_{\\rm{esc}}^{Ly\\alpha}$ correlation is in good qualitative agreement with theoretical predictions and provides further evidence that estimates of $f_{\\rm{esc}}^{\\rm{LyC}}$ within the Epoch of Reionization should be based on proxies sensitive to neutral gas density/geometry and dust attenuation.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-06-06T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "escape fraction",
      "star-forming galaxies",
      "lyman-continuum photons",
      "equivalent width",
      "lyman-alpha"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 12,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}