Publication details for Professor Ian SmailChapman, S.C., Bertoldi, F., Smail, I., Blain, A.W., Geach, J.E., Gurwell, M., Ivison, R.J., Petitpas, G.R., Reddy, N. & Steidel, C.C. (2015). A blind CO detection of a distant red galaxy in the HS1700+64 protocluster. Monthly Notices of the Royal Astronomical Society: Letters 449(1): L68-L72.
- Publication type: Journal Article
- ISSN/ISBN: 1745-3925 (print), 1745-3933 (online)
- DOI: 10.1093/mnrasl/slv010
- Keywords: ISM: molecules, Galaxies: clusters: general, Galaxies: high-redshift, Galaxies: starburst.
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Author(s) from Durham
We report the blind detection of 12CO 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 12CO(3–2) from galaxies lying in the protocluster at z = 2.300 in the field HS1700+64. If indeed this line in DRG55 is 12CO(3–2), its detection at 104.9 GHz indicates zCO = 2.296. None of the other eight known z ∼ 2.30 protocluster galaxies lying within the primary beam (PB) are detected in 12CO, although the limits are ∼2 × worse towards the edge of the PB where several lie. The optical/near-IR magnitudes of DRG55 (RAB > 27, KAB = 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 (∼1011 M⊙) and 12CO line luminosity (3.6 × 1010 K km s−1 pc2) are comparable to other normal 12CO-detected star-forming galaxies in the literature, although the galaxy is some ∼2 mag (∼6 ×) fainter in the rest-frame UV than 12CO-detected galaxies at z > 2. The detection of DRG55 in 12CO complements three other 12CO 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 12CO in this overdense environment is warranted.