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CO interferometry of gas-rich spiral galaxies in the outskirts of an intermediate redshift cluster

Geach, James E. and Smail, Ian and Coppin, Kristen and Moran, Sean M. and Edge, Alastair C. and Ellis, Richard S. (2009) CO interferometry of gas-rich spiral galaxies in the outskirts of an intermediate redshift cluster. Monthly Notices of the Royal Astronomical Society, 395 (1). L62-L66. ISSN 0035-8711.

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We present IRAM Plateau de Bure Interferometer 3-mm observations of CO J(1 → 0) emission in two 24-μm selected starburst galaxies in the outskirts (∼2–3R_(virial)) of the rich cluster Cl 0024+16 (z= 0.395) . The galaxies' inferred far-infrared luminosities place them in the luminous infrared galaxy (LIRG) class (L_(FIR) > 10^(11) L_⊙) , with star formation rates of ∼60 M_⊙ yr^(−1) . Strong CO J(1 → 0) emission is detected in both galaxies, and we use the CO line luminosity to estimate the mass of cold molecular gas, M(H_2) . Assuming M(H_2)/L'_(CO)= 0.8 M_⊙ (K km^(−1) pc^2)^(−1) , we estimate M(H_2) = (5.4–9.1) × 10^9 M_⊙ for the two galaxies. We estimate the galaxies' dynamical masses from their CO line widths, M_(dyn)∼ 1–3 × 10^(10) M_⊙ , implying large cold gas fractions in the galaxies' central regions. At their current rates, they will complete the assembly of M_★∼ 10^(10) M_⊙ and double their stellar mass within as little as ∼150 Myr. If these galaxies are destined to evolve into S0s, then the short time-scale for stellar mass assembly implies that their major episode of bulge growth occurs while they are still in the cluster outskirts, long before they reach the core regions. Subsequent fading of the disc component relative to the stellar bulge after the gas reservoirs have been exhausted could complete the transformation of spiral-to-S0.

Item Type:Article
Related URLs:
URLURL TypeDescription
Geach, James E.0000-0003-4964-4635
Smail, Ian0000-0003-3037-257X
Moran, Sean M.0000-0002-9194-5071
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2009 The Authors. Journal compilation. Accepted 2009 February 15. Received 2009 February 13; in original form 2009 January 13. We warmly thank Roberto Neri and Philippe Salomé at IRAM for their assistance in obtaining and reducing this data. We also thank Mark Swinbank for helpful comments. This work is based on observations carried out with the IRAM PdBI. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). JEG is supported by the UK Science and Technology Facilities Council (STFC). KC is a STFC Fellow at Durham University. IS and RSE acknowledge the Royal Society and STFC.
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Max Planck GesellschaftUNSPECIFIED
Instituto Geografico Nacional (IGN)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:galaxies: clusters: individual: Cl0024+16 galaxies: starburst
Issue or Number:1
Record Number:CaltechAUTHORS:20090825-151609468
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15309
Deposited By: Ruth Sustaita
Deposited On:26 Aug 2009 15:44
Last Modified:05 Nov 2019 23:33

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