{
  "id": "0904.3333",
  "version": "v2",
  "published": "2009-04-22T19:03:44.000Z",
  "updated": "2009-07-20T19:51:25.000Z",
  "title": "The Dual Origin of Stellar Halos",
  "authors": [
    "Adi Zolotov",
    "Beth Willman",
    "Alyson M. Brooks",
    "Fabio Governato",
    "Chris B. Brook",
    "David W. Hogg",
    "Tom Quinn",
    "Greg Stinson"
  ],
  "comment": "Version accepted to ApJ. Content is unchanged from previous version, but paper has been restructured for clarity",
  "journal": "Astrophys.J.702:1058-1067,2009",
  "doi": "10.1088/0004-637X/702/2/1058",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We investigate the formation of the stellar halos of four simulated disk galaxies using high resolution, cosmological SPH + N-Body simulations. These simulations include a self-consistent treatment of all the major physical processes involved in galaxy formation. The simulated galaxies presented here each have a total mass of ~10^12 M_sun, but span a range of merger histories. These simulations allow us to study the competing importance of in-situ star formation (stars formed in the primary galaxy) and accretion of stars from subhalos in the building of stellar halos in a LambdaCDM universe. All four simulated galaxies are surrounded by a stellar halo, whose inner regions (r < 20 kpc) contain both accreted stars, and an in-situ stellar population. The outer regions of the galaxies' halos were assembled through pure accretion and disruption of satellites. Most of the in-situ halo stars formed at high redshift out of smoothly accreted cold gas in the inner 1 kpc of the galaxies' potential wells, possibly as part of their primordial disks. These stars were displaced from their central locations into the halos through a succession of major mergers. We find that the two galaxies with recently quiescent merger histories have a higher fraction of in-situ stars (~20-50%) in their inner halos than the two galaxies with many recent mergers (~5-10% in-situ fraction). Observational studies concentrating on stellar populations in the inner halo of the Milky Way will be the most affected by the presence of in-situ stars with halo kinematics, as we find that their existence in the inner few tens of kpc is a generic feature of galaxy formation.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2009-07-20T19:51:25.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "stellar halo",
      "dual origin",
      "inner halo",
      "galaxy formation",
      "in-situ star formation"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "The Astrophysical Journal",
      "year": 2009,
      "month": "Sep",
      "volume": 702,
      "number": 2,
      "pages": 1058
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 818478,
      "adsabs": "2009ApJ...702.1058Z"
    }
  }
}