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Published November 2017 | Published + Submitted
Journal Article Open

The role of molecular gas in galaxy transition in compact groups

Abstract

Compact groups (CGs) provide an environment in which interactions between galaxies and with the intra-group medium enable and accelerate galaxy transitions from actively star forming to quiescent. Galaxies in transition from active to quiescent can be selected, by their infrared (IR) colors, as canyon or infrared transition zone (IRTZ) galaxies. We used a sample of CG galaxies with IR data from the Wide Field Infrared Survey Explorer (WISE) allowing us to calculate the stellar mass and star formation rate (SFR) for each galaxy. Furthermore, we present new CO(1−0) data for 27 galaxies and collect data from the literature to calculate the molecular gas mass for a total sample of 130 galaxies. This data set allows us to study the difference in the molecular gas fraction (M_(mol)/M∗) and star formation efficiency (SFE = SFR/M_(mol)) between active, quiescent, and transitioning (i.e., canyon and IRTZ) galaxies. We find that transitioning galaxies have a mean molecular gas fraction and a mean SFE that are significantly lower than those of actively star-forming galaxies. The molecular gas fraction is higher than that of quiescent galaxies, whereas the SFE is similar. These results indicate that the transition from actively star-forming to quiescent in CG galaxies goes along with a loss of molecular gas, possibly due to tidal forces exerted from the neighboring galaxies or a decrease in the gas density. In addition, the remaining molecular gas loses its ability to form stars efficiently, possibly owing to turbulence perturbing the gas,as seen in other, well-studied examples such as Stephan's Quintet and HCG 57. Thus, the amount and properties of molecular gas play a crucial role in the environmentally driven transition of galaxies from actively star forming to quiescent.

Additional Information

© 2017 ESO. Article published by EDP Sciences. Received 30 March 2017; Accepted 2 August 2017; Published online 22 November 2017. We appreciate very much the useful thoughts and comments from the referee. U.L. acknowledges support by the research projects AYA2014-53506-P from the Spanish Ministerio de Economía y Competitividad, from the European Regional Development Funds (FEDER) and the Junta de Andalucía (Spain) grants FQM108. We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr) and of the Nasa Extragalactic Database (NED, https://ned.ipac.caltech.edu). This work is based on observations carried out under project number 167-16 with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). We would like to thank the IRAM staff at the 30 m telescope warmly for their support during the observations.

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Published - aa30898-17.pdf

Submitted - 1708.09159.pdf

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August 19, 2023
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