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Title: A MOLECULAR EINSTEIN RING TOWARD THE z = 3.93 SUBMILLIMETER GALAXY MM18423+5938

Journal Article · · Astrophysical Journal Letters
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8]
  1. Observatoire de Paris, CNRS, 61 Av. de l'Observatoire, F-75014, Paris (France)
  2. NRAO, Pete V. Domenici Array Science Center, P.O. Box O, Socorro, NM 87801 (United States)
  3. Canada France Hawaii Telescope Corporation, HI 96743 (United States)
  4. Laboratoire d'Astrophysique de Marseille, Observatoire d'Astronomie Marseille-Provence, BP 8, F13376 Marseille (France)
  5. Astronomy Department, Caltech, 1200 East California boulevard, Pasadena, CA 91125 (United States)
  6. Argelander Institute for Astronomy, University of Bonn, Auf dem Hugel 71, 53121 Bonn (Germany)
  7. Max-Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg (Germany)
  8. Institut d'Astrophysique de Paris, 98bis Bld Arago, F75014, Paris (France)

We present high-resolution imaging of the low-order (J = 1 and 2) CO line emission from the z = 3.93 submillimeter galaxy (SMG) MM18423+5938 using the Expanded Very Large Array, and optical and near-IR imaging using the Canada-France-Hawaii Telescope. This SMG with a spectroscopic redshift was thought to be gravitationally lensed given its enormous apparent brightness. We find that the CO emission is consistent with a complete Einstein ring with a major axis diameter of {approx}1.''4, indicative of lensing. We have also identified the lensing galaxy as a very red elliptical coincident with the geometric center of the ring and estimated its photometric redshift z {approx} 1.1. A first estimate of the lens magnification factor is m {approx} 12. The luminosity L'{sub CO(1-0)} of the CO(1-0) emission is 2.71 {+-} 0.38 x 10{sup 11} m {sup -1} K km s{sup -1} pc{sup 2}, and, adopting the commonly used conversion factor for ultraluminous infrared galaxies (ULIRGs), the molecular gas mass is M(H{sub 2}) = 2.2 x 10{sup 11} m {sup -1} M{sub sun}, comparable to unlensed SMGs if corrected by m {approx} 12. Our revised estimate of the far-IR luminosity of MM18423+5938 is 2 x 10{sup 13} m {sup -1} < L{sub FIR} < 3 x 10{sup 14} m {sup -1} L{sub sun}, comparable to that of ULIRGs. Further observations are required to quantify the star formation rate in MM18423+5938 and to constrain the mass model of the lens in more detail.

OSTI ID:
21565465
Journal Information:
Astrophysical Journal Letters, Vol. 739, Issue 1; Other Information: DOI: 10.1088/2041-8205/739/1/L30; ISSN 2041-8205
Country of Publication:
United States
Language:
English