{
  "id": "1710.06171",
  "version": "v1",
  "published": "2017-10-17T09:03:08.000Z",
  "updated": "2017-10-17T09:03:08.000Z",
  "title": "The impact of Lyman-$α$ radiative transfer on large-scale clustering in the Illustris simulation",
  "authors": [
    "C. Behrens",
    "C. Byrohl",
    "S. Saito",
    "J. C. Niemeyer"
  ],
  "comment": "11 pages, submitted to A&A",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "Lyman-$\\alpha$ emitters (LAEs) are a promising probe of the large-scale structure at high redshift, $z\\gtrsim 2$. In particular, the Hobby-Eberly Telescope Dark Energy Experiment aims at observing LAEs at 1.9 $<z<$ 3.5 to measure the Baryon Acoustic Oscillation (BAO) scale and the Redshift-Space Distortion (RSD). However, Zheng et al. (2011) pointed out that the complicated radiative transfer (RT) of the resonant Lyman-$\\alpha$ emission line generates an anisotropic selection bias in the LAE clustering on large scales, $s\\gtrsim 10$ Mpc. This effect could potentially induce a systematic error in the BAO and RSD measurements. Also, Croft et al. (2016) claims an observational evidence of the effect in the Lyman-$\\alpha$ intensity map, albeit statistically insignificant. We aim at quantifying the impact of the Lyman-$\\alpha$ RT on the large-scale galaxy clustering in detail. For this purpose, we study the correlations between the large-scale environment and the ratio of an apparent Lyman-$\\alpha$ luminosity to an intrinsic one, which we call the `observed fraction', at $2<z<6$. We apply our Lyman-$\\alpha$ RT code by post-processing the full Illustris simulations. We simply assume that the intrinsic luminosity of the Lyman-$\\alpha$ emission is proportional to the star formation rate of galaxies in Illustris, yielding a sufficiently large sample of LAEs to measure the anisotropic selection bias. We find little correlations between large-scale environment and the observed fraction induced by the RT, and hence a smaller anisotropic selection bias than what was claimed by Zheng et al. (2011). We argue that the anisotropy was overestimated in the previous work due to the insufficient spatial resolution: it is important to keep the resolution such that it resolves the high density region down to the scale of the interstellar medium, $\\sim1$ physical kpc. (abridged)",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-10-17T09:03:08.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "illustris simulation",
      "radiative transfer",
      "large-scale clustering",
      "telescope dark energy experiment aims",
      "hobby-eberly telescope dark energy experiment"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 11,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}