2006/07/05 by L. J. Hainline, Laura J. Hainline, A. W. Blain +5 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Brightness #Brightness temperature #Emission spectrum #Excited state #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Green Bank Telescope #Line (geometry) #Telescope #astro-ph
paper · pdf · doi:10.1086/507443
published as Astrophys.J.650:614-623,2006 · 11 pages, accepted for publication in The Astrophysical Journal
arxiv created 2006/07/05 · openalex publication_date 2006/10/18 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We report the first detection of CO (1→0) emission from a submillimeter-selected galaxy, using the Green Bank Telescope. We identify the line in the spectrum of SMM J13120+4242 as a broad emission feature at z = 3.408, with Δ V FWHM = 1040 ± 190 km s -1 . If the observed CO (1→0) line profile arises from a single object and not several merging objects, then the CO (4 → 3)/CO (1 → 0) brightness temperature ratio of ~0.26 suggests n (H 2 ) > (3-10) × 10 2 cm -3 and the presence of subthermally excited gas. The integrated line flux implies a cold molecular gas mass M (H 2 ) = 1.6 × 10 11 M ☉ , comparable to the dynamical mass estimate and 4 times larger than the H 2 mass predicted from the CO (4→3) line, assuming a brightness temperature ratio of 1.0. While our observations confirm that this submillimeter galaxy is massive and gas-rich, they also suggest that extrapolating gas masses from J upper ≥ 3 transitions of CO leads to considerable uncertainties. We also report an upper limit to the mass of cold molecular gas in a second submillimeter galaxy, SMM J09431+4700, of M (H 2 ) ≲ 4 × 10 10 M ☉ .