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Date and Time of the Query: 2019-03-26 T11:10:06 PDT
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For refcode 2015A&A...573A.111O:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2015A&A...573A.111O Cold gas in group-dominant elliptical galaxies O'Sullivan, E.; Combes, F.; Hamer, S.; Salome, P.; Babul, A.; Raychaudhury, S. Abstract. We present IRAM 30 m telescope observations of the CO(1-0) and (2-1) lines in a sample of 11 group-dominant elliptical galaxies selected from the CLoGS nearby groups sample. Our observations confirm the presence of molecular gas in 4 of the 11 galaxies at >4sigma significance, and combining these with data from the literature we find a detection rate of 43 +/- 14%, comparable to the detection rate for nearby radio galaxies, suggesting that group-dominant ellipticals may be more likely to contain molecular gas than their non-central counterparts. Those group-dominant galaxies which are detected typically contain ~ 2 x 10^8^ M_sun_ of molecular gas, and although most have low star formation rates (<1 M_sun_ yr^-1^) they have short depletion times, indicating that the gas must be replenished on timescales ~10^8^ yr. Almost all of the galaxies contain active nuclei, and we note while the data suggest that CO may be more common in the most radio-loud galaxies, the mass of molecular gas required to power the active nuclei through accretion is small compared to the masses observed. We consider possible origin mechanisms for the gas, through cooling of stellar ejecta within the galaxies, group-scale cooling flows, and gas-rich mergers, and find probable examples of each type within our sample, confirming that a variety of processes act to drive the build up of molecular gas in group-dominant ellipticals. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A111 Key words: galaxies: evolution, galaxies: star formation, galaxies: groups: general, galaxies: kinematics and dynamics, galaxies: general
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