{
  "id": "1609.04402",
  "version": "v1",
  "published": "2016-09-14T20:00:00.000Z",
  "updated": "2016-09-14T20:00:00.000Z",
  "title": "The Most Massive Galaxies and Black Holes Allowed by $Λ$CDM",
  "authors": [
    "Peter Behroozi",
    "Joseph Silk"
  ],
  "comment": "4 pages; MNRAS submitted",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Given a galaxy's stellar mass, its host halo mass has a lower limit from the cosmic baryon fraction and known baryonic physics. At $z>4$, galaxy stellar mass functions place lower limits on halo number densities that approach expected $\\Lambda$CDM halo mass functions. High-redshift galaxy stellar mass functions can thus place interesting limits on number densities of massive haloes, which are otherwise very difficult to measure. While halo mass functions at $z<8$ are consistent with observed galaxy stellar masses, JWST and WFIRST will more than double the redshift range over which useful constraints are available. We calculate galaxy stellar masses as a function of redshift that, if they existed in sufficient numbers, would either require unusual baryonic physics or in extreme cases would rule out $\\Lambda$CDM entirely. Extending the calculation to the entire observable Universe, we find that the existence of a single $10^{11}$ M$_\\odot$ galaxy at $z=13$ would rule out Planck $\\Lambda$CDM with >95% confidence. Similar arguments apply to black holes; using number density constraints alone, the most massive observed black holes at $z>5$ must lie above the median $z=0$ black hole mass - bulge mass relation. If their virial mass estimates are accurate, the quasars SDSS J1044$-$0125 and SDSS J010013.02$+$280225.8 must both have black hole mass - stellar mass ratios of at least 2%, equaling the recent $z=0$ record for central galaxies in NGC 1600.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-09-14T20:00:00.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "galaxy stellar mass functions",
      "stellar mass functions place",
      "mass functions place lower",
      "functions place lower limits",
      "massive galaxies"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 4,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}