{
  "id": "0908.1621",
  "version": "v1",
  "published": "2009-08-12T06:25:02.000Z",
  "updated": "2009-08-12T06:25:02.000Z",
  "title": "Dry mergers and the formation of early-type galaxies: constraints from lensing and dynamics",
  "authors": [
    "Carlo Nipoti",
    "Tommaso Treu",
    "Adam S. Bolton"
  ],
  "comment": "ApJ, accepted. 16 pages, 11 figures",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Dissipationless (gas-free or \"dry\") mergers have been suggested to play a major role in the formation and evolution of early-type galaxies, particularly in growing their mass and size without altering their stellar populations. We perform a new test of the dry merger hypothesis by comparing N-body simulations of realistic systems to empirical constraints provided by recent studies of lens early-type galaxies. We find that major and minor dry mergers: i) preserve the nearly isothermal structure of early-type galaxies within the observed scatter; ii) do not change more than the observed scatter the ratio between total mass M and \"virial\" mass R_e*sigma/2G (where R_e is the half-light radius and sigma the projected velocity dispersion); iii) increase strongly galaxy sizes [as M^(0.85+/-0.17)] and weakly velocity dispersions [as M^(0.06+/-0.08)] with mass, thus moving galaxies away from the local observed M-R_e and M-sigma relations; iv) introduce substantial scatter in the M-R_e and M-sigma relations. Our findings imply that, unless there is a high degree of fine tuning of the mix of progenitors and types of interactions, present-day massive early-type galaxies cannot have assembled more than ~50% of their mass, and increased their size by more than a factor ~1.8, via dry merging.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2009-08-12T06:25:02.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "constraints",
      "velocity dispersion",
      "m-sigma relations",
      "dry merger hypothesis",
      "present-day massive early-type galaxies"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/0004-637X/703/2/1531",
      "journal": "The Astrophysical Journal",
      "year": 2009,
      "month": "Oct",
      "volume": 703,
      "number": 2,
      "pages": 1531
    },
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 828326,
      "adsabs": "2009ApJ...703.1531N"
    }
  }
}