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The Nature of Dusty Starburst Galaxies in a Rich Cluster at z = 0.4: The Progenitors of Lenticulars?

Geach, James E. and Smail, Ian and Moran, Sean M. and Treu, Tommaso and Ellis, Richard S. (2009) The Nature of Dusty Starburst Galaxies in a Rich Cluster at z = 0.4: The Progenitors of Lenticulars? Astrophysical Journal, 691 (1). pp. 783-793. ISSN 0004-637X. doi:10.1088/0004-637X/691/1/783.

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We present the results of a Spitzer Infrared Spectrograph survey of 24 μm selected luminous infrared galaxies (LIRGs, LIR > 10^11 L☉) in the rich cluster Cl 0024+16 at z = 0.4. Optically, these LIRGs resemble unremarkable spiral galaxies with e(a)/e(c) spectral classifications and [O II]-derived star formation rates (SFRs) of ≾2 M☉ yr^–1, generally indistinguishable from the "quiescent" star-forming population in the cluster. Our IRS spectra show that the majority of the 24 μm detected galaxies exhibit polycyclic aromatic hydrocarbon emission with implied SFRs ~30-60 M☉ yr^–1, with only one (< 10%) in the sample displaying unambiguous evidence of an active galactic nucleus in the mid-infrared. This confirms the presence of a large population of obscured starburst galaxies in distant clusters, which comprise the bulk of the star formation occurring in these environments at z ~0.5. We suggest that, although several mechanisms could be at play, these dusty starbursts could be the signature of an important evolutionary transition converting gas-rich spiral galaxies in distant clusters into the passive, bulge-dominated lenticular galaxies that become increasingly abundant in the cores of rich clusters in the ~4 Gyr to the present day.

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
Treu, Tommaso0000-0002-8460-0390
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2009. The American Astronomical Society. Received 2008 July 11; accepted 2009 September 22; published 2009 January 19. Print publication: Issue 1 (2009 January 20). The authors thank an anonymous referee for a careful and insightful report that has improved the quality of this paper, and John Lucey, Lauren MacArthur, Mark Norris, Russell Smith, J. D. Smith, Mark Swinbank, and Bianca Poggianti for helpful discussions, and Oliver Czoske for providing optical spectra for some of the LIRGs. J.E.G. is supported by the UK Science and Technology Facilities Council. I.R.S. and R.S.E. acknowledge support from the Royal Society. T.T. acknowledges support from the National Science Foundation through CAREER award NSF-0642621, by the Sloan Foundation through a Sloan Research Fellowship, and by the Packard Foundation through a Packard Fellowship. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory (JPL), California Institute of Technology, under NASA contract 1407. Support from NASA though a JPL grant in support of Spitzer proposals GO 3143 and GO 30621 is gratefully acknowledged.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
JPLGO 3143
JPLGO 30621
Subject Keywords:galaxies: clusters: individual (Cl0024+16); galaxies: evolution; galaxies: starburst
Issue or Number:1
Record Number:CaltechAUTHORS:GEAapj09
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13110
Deposited By: Archive Administrator
Deposited On:21 Jan 2009 18:55
Last Modified:08 Nov 2021 22:35

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