EXTENDED COLD MOLECULAR GAS RESERVOIRS IN z {approx_equal} 3.4 SUBMILLIMETER GALAXIES

Journal Article · Tue Sep 20 04:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/739/1/L31· OSTI ID:21565466

Riechers, Dominik A ^[1]; Hodge, Jacqueline; Walter, Fabian ^[2]; Carilli, Christopher L ^[3]; Bertoldi, Frank ^[4]

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1. Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
2. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
3. National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States)
4. Argelander-Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)

We report the detection of spatially resolved CO(J = 1{yields}0) emission in the z {approx} 3.4 submillimeter galaxies (SMGs) SMM J09431+4700 and SMM J13120+4242, using the Expanded Very Large Array (EVLA). SMM J09431+4700 is resolved into the two previously reported millimeter sources H6 and H7, separated by {approx}30 kpc in projection. We derive CO(J = 1{yields}0) line luminosities of L'{sub CO(1-0)} = (2.49 {+-} 0.86) and (5.82 {+-} 1.22) x 10{sup 10} K km s{sup -1} pc{sup 2} for H6 and H7, and L'{sub CO(1-0)} = (23.4 {+-} 4.1) x 10{sup 10} K km s{sup -1} pc{sup 2} for SMM J13120+4242. These are {approx}1.5-4.5 times higher than what is expected from simple excitation modeling of higher-J CO lines, suggesting the presence of copious amounts of low-excitation gas. This is supported by the finding that the CO(J = 1{yields}0) line in SMM J13120+4242, the system with the lowest CO excitation, appears to have a broader profile and more extended spatial structure than seen in higher-J CO lines (which is less prominently seen in SMM J09431+4700). Based on L'{sub CO(1-0)} and excitation modeling, we find M{sub gas} = 2.0-4.3 and 4.7-12.7x10{sup 10} M{sub sun} for H6 and H7, and M{sub gas} = 18.7-69.4x10{sup 10} M{sub sun} for SMM J13120+4242. The observed CO(J = 1{yields}0) properties are consistent with the picture that SMM J09431+4700 represents an early-stage, gas-rich major merger and that SMM J13120+4242 represents such a system in an advanced stage. This study thus highlights the importance of spatially and dynamically resolved CO(J = 1{yields}0) observations of SMGs to further understand the gas physics that drive star formation in these distant galaxies, which is possible only now that the EVLA is rising to its full capabilities.

• OSTI ID: 21565466
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 739; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
EMISSION
ENERGY-LEVEL TRANSITIONS
EXCITATION
GALAXIES
OXIDES
OXYGEN COMPOUNDS
SIMULATION