A large mass of H2 in the brightest cluster galaxy in Zwicky 3146

E. Egami, G. H. Rieke, D. Fadda, D. C. Hines

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52 Scopus citations


We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous (LIR = 4 × 1011 L⊙ brightest cluster galaxy (BCG) in the X-ray-luminous cluster Zwicky 3146 (Z3146; z = 0.29). The spectrum shows strong aromatic emission features, indicating that the dominant source of the infrared luminosity is star formation. The most striking feature of the spectrum, however, is the exceptionally strong molecular hydrogen (H 2) emission lines, which seem to be shock-excited. The line luminosities and inferred warm H2 gas mass (∼10 M⊙) are 6 times larger than those of NGC 6240, the most H 2-luminous galaxy at z =s 0.05. Together with the large amount of cold H2 detected previously (∼1011 M⊙), this indicates that the Z3146 BCG contains disproportionately large amounts of both warm and cold H2 gas for its infrared luminosity, which may be related to the intracluster gas cooling process in the cluster core.

Original languageEnglish (US)
Pages (from-to)L21-L24
JournalAstrophysical Journal
Issue number1 II
StatePublished - Nov 20 2006


  • Cooling flows
  • Galaxies: active
  • Galaxies: clusters: general galaxies: elliptical and lenticular, cD
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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