We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

A blind CO detection of a distant red galaxy in the HS1700+64 protocluster.

Chapman, S.C. and Bertoldi, F. and Smail, I. and Blain, A.W. and Geach, J.E. and Gurwell, M. and Ivison, R.J. and Petitpas, G.R. and Reddy, N. and 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.


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.

Item Type:Article
Keywords:ISM: molecules, Galaxies: clusters: general, Galaxies: high-redshift, Galaxies: starburst.
Full text:(VoR) Version of Record
Download PDF
Publisher Web site:
Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:19 January 2015
Date deposited:22 February 2016
Date of first online publication:May 2015
Date first made open access:No date available

Save or Share this output

Look up in GoogleScholar