REDSHIFT DETERMINATION AND CO LINE EXCITATION MODELING FOR THE MULTIPLY LENSED GALAXY HLSW-01

Journal Article · Fri May 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/733/1/29· OSTI ID:21576810

Scott, K S; Lupu, R E; Aguirre, J E ^[1]; Auld, R; Eales, S ^[2]; Aussel, H; Chanial, P ^[3]; Baker, A J ^[4]; Beelen, A ^[5]; Bock, J; Bradford, C M; Carpenter, J M; Cooray, A; Dowell, C D ^[6]; Brisbin, D ^[7]; Burgarella, D ^[8]; Chapman, S C ^[9]; Clements, D L ^[10]; Conley, A ^[11]; Cox, P ^[12]

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1. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)
2. School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom)
3. Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France)
4. Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)
5. Institut d'Astrophysique Spatiale (IAS), batiment 121, Universite Paris-Sud 11 and CNRS (UMR 8617), 91405 Orsay (France)
6. California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
7. Space Science Building, Cornell University, Ithaca, NY 14853-6801 (United States)
8. Laboratoire d'Astrophysique de Marseille, OAMP, Universite Aix-marseille, CNRS, 38 rue Frederic Joliot-Curie, 13388 Marseille Cedex 13 (France)
9. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
10. Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
11. Center for Astrophysics and Space Astronomy 389-UCB, University of Colorado, Boulder, CO 80309 (United States)
12. Institut de Radioastronomie Millimetrique, 300 Rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'Heres (France)

We report on the redshift measurement and CO line excitation of HERMES J105751.1+573027 (HLSW-01), a strongly lensed submillimeter galaxy discovered in Herschel/SPIRE observations as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). HLSW-01 is an ultra-luminous galaxy with an intrinsic far-infrared luminosity of L{sub FIR} = 1.4 x 10{sup 13} L{sub sun}, and is lensed by a massive group of galaxies into at least four images with a total magnification of {mu} = 10.9 {+-} 0.7. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify a redshift of z = 2.958 {+-} 0.007 for this source, using the simultaneous detection of four CO emission lines (J = 7 {yields} 6, J = 8 {yields} 7, J = 9 {yields} 8, and J = 10 {yields} 9). Combining the measured line fluxes for these high-J transitions with the J = 1 {yields} 0, J = 3 {yields} 2, and J = 5 {yields} 4 line fluxes measured with the Green Bank Telescope, the Combined Array for Research in Millimeter Astronomy, and the Plateau de Bure Interferometer, respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full CO spectral line energy distribution is described well by warm, moderate-density gas with T{sub kin} = 86-235 K and n{sub H{sub 2}} = (1.1-3.5) x 10{sup 3} cm{sup -3}. However, it is possible that the highest-J transitions are tracing a small fraction of very dense gas in molecular cloud cores, and two-component models that include a warm/dense molecular gas phase with T{sub kin} {approx} 200 K, n{sub H{sub 2}}{approx}10{sup 5} cm{sup -3} are also consistent with these data. Higher signal-to-noise measurements of the J{sub up} {>=} 7 transitions with high spectral resolution, combined with high spatial resolution CO maps, are needed to improve our understanding of the gas excitation, morphology, and dynamics of this interesting high-redshift galaxy.

• OSTI ID: 21576810
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 733; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
EXCITATION
FAR INFRARED RADIATION
GALAXIES
INFRARED RADIATION
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
RED SHIFT
SIMULATION