{
  "id": "1710.10053",
  "version": "v1",
  "published": "2017-10-27T09:55:07.000Z",
  "updated": "2017-10-27T09:55:07.000Z",
  "title": "A new model framework for circumgalactic Ly$α$ radiative transfer constrained by galaxy-Ly$α$ forest clustering",
  "authors": [
    "Koki Kakiichi",
    "Mark Dijkstra"
  ],
  "comment": "20 pages, 14 figures, submitted to MNRAS",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We present a new perturbative approach to \"constrained Ly$\\alpha$ radiative transfer'\" (RT) through the circum- and inter-galactic medium (CGM and IGM). We constrain the HI content and kinematics of the CGM and IGM in a physically motivated model, using the galaxy-Ly$\\alpha$ forest clustering data from spectroscopic galaxy surveys in QSO fields at $z\\sim2-3$. This enables us to quantify the impact of the CGM/IGM on Ly$\\alpha$ emission in an observationally constrained, realistic cosmological environment. Our model predicts that the CGM and IGM at these redshifts transmit $\\approx80~\\%$ of Ly$\\alpha$ photons after having escaped from galaxies. This implies that while the inter-stellar medium primarily regulates Ly$\\alpha$ escape, the CGM has a non-negligible impact on the observed Ly$\\alpha$ line properties and the inferred Ly$\\alpha$ escape fraction, even at $z\\sim 2-3$. Ly$\\alpha$ scattering in the CGM and IGM further introduces an environmental dependence in the (apparent) Ly$\\alpha$ escape fraction, and the observed population of Ly$\\alpha$ emitting galaxies: the CGM/IGM more strongly suppresses direct Ly$\\alpha$ emission from galaxies in overdense regions in the Universe, and redistributes this emission into brighter Ly$\\alpha$ haloes. The resulting mean surface brightness profile of the Ly$\\alpha$ haloes is generally found to be a power-law $\\propto r^{-2.4}$. Our results demonstrate how (integral field) spectroscopic surveys of galaxies in QSO fields constrain circumgalactic Ly$\\alpha$ RT, and we discuss the potential of these models for studying CGM physics, reionization and cosmology.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-10-27T09:55:07.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "radiative transfer",
      "model framework",
      "forest clustering",
      "fields constrain circumgalactic ly",
      "mean surface brightness profile"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}