{
  "id": "1703.09234",
  "version": "v1",
  "published": "2017-03-27T18:00:06.000Z",
  "updated": "2017-03-27T18:00:06.000Z",
  "title": "Constraints on Quenching of $z\\lesssim2$ Massive Galaxies from the Evolution of the average Sizes of Star-Forming and Quenched Populations in COSMOS",
  "authors": [
    "A. L. Faisst",
    "C. M. Carollo",
    "P. L. Capak",
    "S. Tacchella",
    "A. Renzini",
    "O. Ilbert",
    "H. J. McCracken",
    "N. Z. Scoville"
  ],
  "comment": "20 pages, 9 figures, 1 table, accepted for publication in ApJ",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We use $>$9400 $\\log(m/M_{\\odot})>10$ quiescent and star-forming galaxies at $z\\lesssim2$ in COSMOS/UltraVISTA to study the average size evolution of these systems, with focus on the rare, ultra-massive population at $\\log(m/M_{\\odot})>11.4$. The large 2-square degree survey area delivers a sample of $\\sim400$ such ultra-massive systems. Accurate sizes are derived using a calibration based on high-resolution images from the Hubble Space Telescope. We find that, at these very high masses, the size evolution of star-forming and quiescent galaxies is almost indistinguishable in terms of normalization and power-law slope. We use this result to investigate possible pathways of quenching massive $m>M^*$ galaxies at $z<2$. We consistently model the size evolution of quiescent galaxies from the star-forming population by assuming different simple models for the suppression of star-formation. These models include an instantaneous and delayed quenching without altering the structure of galaxies and a central starburst followed by compaction. We find that instantaneous quenching reproduces well the observed mass-size relation of massive galaxies at $z>1$. Our starburst$+$compaction model followed by individual growth of the galaxies by minor mergers is preferred over other models without structural change for $\\log(m/M_{\\odot})>11.0$ galaxies at $z>0.5$. None of our models is able to meet the observations at $m>M^*$ and $z<1$ with out significant contribution of post-quenching growth of individual galaxies via mergers. We conclude that quenching is a fast process in galaxies with $ m \\ge 10^{11} M_\\odot$, and that major mergers likely play a major role in the final steps of their evolution.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-03-27T18:00:06.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "massive galaxies",
      "average size",
      "quenched populations",
      "star-forming",
      "size evolution"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 20,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}