Lestrade, Jean-François and Carilli, Chris L. and Thanjavur, Karun and Kneib, Jean-Paul and Riechers, Dominik A. and Bertoldi, Frank and Walter, Fabian and Omont, Alain (2011) A Molecular Einstein Ring Toward the z = 3.93 Submillimeter Galaxy MM18423+5938. Astrophysical Journal Letters, 739 (1). Art. No. L30. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20110929-095438603
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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 ~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 ~ 1.1. A first estimate of the lens magnification factor is m ~ 12. The luminosity L'_(CO(1–0)) of the CO(1-0) emission is 2.71 ± 0.38 × 10^(11) m^(–1) K km s^(–1) pc^2, and, adopting the commonly used conversion factor for ultraluminous infrared galaxies (ULIRGs), the molecular gas mass is M(H_2) = 2.2 × 10^(11) m^(–1) M_☉, comparable to unlensed SMGs if corrected by m ~ 12. Our revised estimate of the far-IR luminosity of MM18423+5938 is 2 × 10^(13) m^(–1) < L_(FIR) < 3 × 10^(14) m^(–1) L_☉, 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.
|Additional Information:||© 2011 The American Astronomical Society. Received 2011 April 12; accepted 2011 May 27; published 2011 August 29. We acknowledge and sincerely thank Dr. S. D. J. Gwyn (CADC, Victoria, Canada) for promptly stacking the CFHT Elixir processed MegaCam data with MegaPipe. This work is based on EVLA observations conducted under the auspices of NRAO, WirCam and MegaCam observations conducted at CFHT, and on use of data products from the Two Micron All Sky Survey (2MASS). Facilities: EVLA, CFHT|
|Subject Keywords:||galaxies: evolution; galaxies: high-redshift; galaxies: ISM; galaxies: starburst; gravitational lensing: strong; submillimeter: galaxies|
|Classification Code:||PACS: 95.85.Fm; 98.62.Ai; 98.62.Sb; 98.62.Py|
|Official Citation:||A Molecular Einstein Ring Toward the z = 3.93 Submillimeter Galaxy MM18423+5938 Jean-François Lestrade et al. 2011 ApJ 739 L30|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||29 Sep 2011 21:19|
|Last Modified:||26 Dec 2012 13:43|
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