{
  "id": "1807.08761",
  "version": "v1",
  "published": "2018-07-23T18:00:04.000Z",
  "updated": "2018-07-23T18:00:04.000Z",
  "title": "The role of mergers in driving morphological transformation over cosmic time",
  "authors": [
    "G. Martin",
    "S. Kaviraj",
    "J. E. G. Devriendt",
    "Y. Dubois",
    "C. Pichon"
  ],
  "comment": "Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Understanding the processes that trigger morphological transformation is central to understanding how and why the Universe transitions from being disc-dominated at early epochs to having the morphological mix that is observed today. We use Horizon-AGN, a cosmological hydrodynamical simulation, to perform a comprehensive study of the processes that drive morphological change in massive (M > 10^10 MSun) galaxies over cosmic time. We show that (1) essentially all the morphological evolution in galaxies that are spheroids at z=0 is driven by mergers with mass ratios greater than 1:10, (2) major mergers alone cannot produce today's spheroid population -- minor mergers are responsible for a third of all morphological transformation over cosmic time and are its dominant driver after z~1, (3) prograde mergers trigger milder morphological transformation than retrograde mergers -- while both types of events produce similar morphological changes at z>2, the average change due to retrograde mergers is around twice that due to their prograde counterparts at z~0, (4) remnant morphology depends strongly on the gas fraction of a merger, with gas-rich mergers routinely re-growing discs, and (5) at a given stellar mass, discs do not exhibit drastically different merger histories from spheroids -- disc survival in mergers is driven by acquisition of cold gas (via cosmological accretion and gas-rich interactions) and a preponderance of prograde mergers in their merger histories.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-07-23T18:00:04.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "cosmic time",
      "driving morphological transformation",
      "produce similar morphological changes",
      "mergers routinely re-growing discs",
      "retrograde mergers"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}