Publication Date:
2015-03-06
Description:
We report the blind detection of 12 CO emission from a distant red galaxy, HS1700.DRG55. We have used the IRAM Plateau de Bure Interferometer WideX, with its 3.6 GHz of instantaneous dual-polarization bandwidth, to target 12 CO(3–2) from galaxies lying in the protocluster at z = 2.300 in the field HS1700+64. If indeed this line in DRG55 is 12 CO(3–2), its detection at 104.9 GHz indicates z CO = 2.296. None of the other eight known z ~ 2.30 protocluster galaxies lying within the primary beam (PB) are detected in 12 CO, although the limits are ~2 worse towards the edge of the PB where several lie. The optical/near-IR magnitudes of DRG55 ( R AB 〉 27, K AB = 22.3) mean that optical spectroscopic redshifts are difficult with 10-m-class telescopes, but near-IR redshifts would be feasible. The 24-μm-implied star formation rate (210 M yr –1 ), stellar mass (~10 11 M ) and 12 CO line luminosity (3.6 10 10 K km s –1 pc 2 ) are comparable to other normal 12 CO-detected star-forming galaxies in the literature, although the galaxy is some ~2 mag (~6 x ) fainter in the rest-frame UV than 12 CO-detected galaxies at z 〉 2. The detection of DRG55 in 12 CO complements three other 12 CO detected UV-bright galaxies in this protocluster from previous studies, and suggests that many optically faint galaxies in the protocluster may host substantial molecular gas reservoirs, and a full blind census of 12 CO in this overdense environment is warranted.
Print ISSN:
1745-3925
Electronic ISSN:
1745-3933
Topics:
Physics
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