{
  "id": "2011.05331",
  "version": "v1",
  "published": "2020-11-10T19:00:00.000Z",
  "updated": "2020-11-10T19:00:00.000Z",
  "title": "The galaxy-halo connection of emission-line galaxies in IllustrisTNG",
  "authors": [
    "Boryana Hadzhiyska",
    "Sandro Tacchella",
    "Sownak Bose",
    "Daniel J. Eisenstein"
  ],
  "comment": "18 pages, 12 figures, 2 tables; feel welcome to email",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We employ the hydrodynamical simulation IllustrisTNG-300-1 to explore the halo occupation distribution (HOD) and environmental dependence of luminous star-forming emission-line galaxies (ELGs) at $z \\sim 1$. Such galaxies are key targets for current and upcoming cosmological surveys. We select model galaxies through cuts in color-color space allowing for a direct comparison with the Extended Baryon Oscillation Spectroscopic Survey and the Dark Energy Spectroscopic Instrument (DESI) surveys and then compare them with galaxies selected based on star-formation rate (SFR) and stellar mass. We demonstrate that the ELG populations are twice more likely to reside in lower-density regions (sheets) compared with the mass-selected populations and twice less likely to occupy the densest regions of the cosmic web (knots). We also show that the color-selected and SFR-selected ELGs exhibit very similar occupation and clustering statistics, finding that the agreement is best for lower redshifts. In contrast with the mass-selected sample, the occupation of halos by a central ELG peaks at $\\sim$20\\%. We furthermore explore the dependence of the HOD and the auto-correlation on environment, noticing that at fixed halo mass, galaxies in high-density regions cluster about 10 times more strongly than low-density ones. This result suggests that we should model carefully the galaxy-halo relation and implement assembly bias effects into our models (estimated at $\\sim$4\\% of the clustering of the DESI color-selected sample at $z = 0.8$). Finally, we apply a simple mock recipe to recover the clustering on large scales ($r \\gtrsim 1 \\ {\\rm Mpc}/h$) to within 1\\% by augmenting the HOD model with an environment dependence, demonstrating the power of adopting flexible population models.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-11-10T19:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "emission-line galaxies",
      "galaxy-halo connection",
      "extended baryon oscillation spectroscopic survey",
      "illustristng",
      "dark energy spectroscopic instrument"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}