Molecular Gas in the z = 1.2 Ultraluminous Merger GOODS J123634.53+621241.3

June 2008 • 2008ApJ...680L..21F

Authors • Frayer, David T. • Koda, Jin • Pope, Alexandra • Huynh, Minh T. • Chary, Ranga-Ram • Scott, Douglas • Dickinson, Mark • Bock, Douglas C. -J. • Carpenter, John M. • Hawkins, David • Hodges, Mark • Lamb, James W. • Plambeck, Richard L. • Pound, Marc W. • Scott, Stephen L. • Scoville, Nicholas Z. • Woody, David P.

Abstract • We report the detection of CO(2→1) emission from the z = 1.2 ultraluminous infrared galaxy (ULIRG) GOODS J123634.53+621241.3 (also known as the submillimeter galaxy GN 26). These observations represent the first discovery of high-redshift CO emission using the new Combined Array for Research in Millimeter-Wave Astronomy (CARMA). Of all high-redshift (z > 1) galaxies within the GOODS-North field, this source has the largest far-infrared (FIR) flux observed in the Spitzer 70 and 160 μm bands. The CO redshift confirms the optical identification of the source, and the bright CO(2→1) line suggests the presence of a large molecular gas reservoir of about 7 × 10¹⁰ M_⊙. The infrared-to-CO luminosity ratio of L(IR)/L^'(CO) = 80 +/- 30 L_⊙ (K km s^-1 pc²)^-1 is slightly smaller than the average ratio found in local ULIRGs and high-redshift submillimeter galaxies. The short star formation timescale of about 70 Myr is consistent with a starburst associated with the merger event and is much shorter than the timescales for spiral galaxies and estimates made for high-redshift galaxies selected on the basis of their B - z and z - K colors.

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Ranga-Ram Chary

Senior Scientist