{
  "id": "1707.04259",
  "version": "v1",
  "published": "2017-07-13T18:00:01.000Z",
  "updated": "2017-07-13T18:00:01.000Z",
  "title": "The impact of chemistry on the structure of high-z galaxies",
  "authors": [
    "A. Pallottini",
    "A. Ferrara",
    "S. Bovino",
    "L. Vallini",
    "S. Gallerani",
    "R. Maiolino",
    "S. Salvadori"
  ],
  "comment": "18 pages, 13 Figures 1 Table, accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "To improve our understanding of high-z galaxies we study the impact of H$_{2}$ chemistry on their evolution, morphology and observed properties. We compare two zoom-in high-resolution (30 pc) simulations of prototypical $M_{\\star}\\sim 10^{10} {\\rm M}_{\\odot}$ galaxies at $z=6$. The first, \"Dahlia\", adopts an equilibrium model for H$_{2}$ formation, while the second, \"Alth{\\ae}a\", features an improved non-equilibrium chemistry network. The star formation rate (SFR) of the two galaxies is similar (within 50\\%), and increases with time reaching values close to 100 ${\\rm M}_{\\odot}/\\rm yr$ at $z=6$. They both have SFR-stellar mass relation consistent with observations, and a specific SFR of $\\simeq 5\\, {\\rm Gyr}^{-1}$. The main differences arise in the gas properties. The non-equilibrium chemistry determines the H$\\rightarrow$ H$_{2}$~transition to occur at densities $> 300\\,{cm}^{-3}$, i.e. about 10 times larger than predicted by the equilibrium model used for Dahlia. As a result, Alth{\\ae}a features a more clumpy and fragmented morphology, in turn making SN feedback more effective. Also, because of the lower density and weaker feedback, Dahlia sits $3\\sigma$ away from the Schmidt-Kennicutt relation; Alth{\\ae}a, instead nicely agrees with observations. The different gas properties result in widely different observables. Alth{\\ae}a outshines Dahlia by a factor of 7 (15) in [CII]~$157.74\\,\\mu{\\rm m}$ (H$_{2}$~$17.03\\,\\mu{\\rm m}$) line emission. Yet, Alth{\\ae}a is under-luminous with respect to the locally observed [CII]-SFR relation. Whether this relation does not apply at high-z or the line luminosity is reduced by CMB and metallicity effects remains as an open question.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-07-13T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "high-z galaxies",
      "equilibrium model",
      "sfr-stellar mass relation consistent",
      "metallicity effects remains",
      "non-equilibrium chemistry network"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}