{
  "id": "1409.4776",
  "version": "v1",
  "published": "2014-09-16T20:00:14.000Z",
  "updated": "2014-09-16T20:00:14.000Z",
  "title": "Discovery of a close pair of faint dwarf galaxies in the halo of Centaurus A",
  "authors": [
    "D. Crnojević",
    "D. J. Sand",
    "N. Caldwell",
    "P. Guhathakurta",
    "B. McLeod",
    "A. Seth",
    "J. Simon",
    "J. Strader",
    "E. Toloba"
  ],
  "comment": "7 pages, 4 figures; ApJL submitted",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "As part of the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) we report the discovery of a pair of faint dwarf galaxies (CenA-MM-Dw1 and CenA-MM-Dw2) at a projected distance of $\\sim$90 kpc from the nearby elliptical galaxy NGC5128 (CenA). We measure a tip of the red giant branch distance to each dwarf, finding $D=3.63 \\pm 0.41$ Mpc for CenA-MM-Dw1 and $D=3.60 \\pm 0.41$ Mpc for CenA-MM-Dw2, both of which are consistent with the distance to NGC5128. A qualitative analysis of the color magnitude diagrams indicates stellar populations consisting of an old, metal-poor red giant branch ($\\gtrsim 12$ Gyr, [Fe/H]$\\sim-1.7$ to -1.9). In addition, CenA-MM-Dw1 seems to host an intermediate-age population as indicated by its candidate asymptotic giant branch stars. The derived luminosities ($M_V=-10.9\\pm0.3$ for CenA-MM-Dw1 and $-8.4\\pm0.6$ for CenA-MM-Dw2) and half-light radii ($r_{h}=1.4\\pm0.04$ kpc for CenA-MM-Dw1 and $0.36\\pm0.08$ kpc for CenA-MM-Dw2) are consistent with those of Local Group dwarfs. CenA-MM-Dw1's low central surface brightness ($\\mu_{V,0}=27.3\\pm0.1$ mag/arcsec$^2$) places it among the faintest and most extended M31 satellites. Most intriguingly, CenA-MM-Dw1 and CenA-MM-Dw2 have a projected separation of only 3 arcmin ($\\sim3$ kpc): we are possibly observing the first, faint satellite of a satellite in an external group of galaxies.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-09-16T20:00:14.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "faint dwarf galaxies",
      "close pair",
      "red giant branch",
      "cena-mm-dw1s low central surface brightness",
      "cena-mm-dw2"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1088/2041-8205/795/2/L35",
      "journal": "The Astrophysical Journal",
      "year": 2014,
      "month": "Nov",
      "volume": 795,
      "number": 2
    },
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2014ApJ...795L..35C"
    }
  }
}