ALMA/ACA CO Survey of the IC 1459 and NGC 4636 Groups: Environmental Effects on the Molecular Gas of Group Galaxies

Bumhyun Lee, Jing Wang, Aeree Chung, Luis C. Ho, Ran Wang, Tomonari Michiyama, Juan Molina, Yongjung Kim, Li Shao, Virginia Kilborn, Shun Wang, Xuchen Lin, Dawoon E. Kim, Barbara Catinella, Luca Cortese, Nathan Deg, Helga Denes, Ahmed Elagali, Bi-Qing For, Dane KleinerBarbel S. Koribalski, Karen Lee-Waddell, Jonghwan Rhee, Kristine Spekkens, Tobias Westmeier, O. Ivy Wong, Frank Bigiel, Albert Bosma, Benne W. Holwerda, Jan M. van der Hulst, Sambit Roychowdhury, Lourdes Verdes-Montenegro, Martin A. Zwaan

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10 Citations (Scopus)


We present new results of a (CO)-C-12(J = 1-0) imaging survey using the Atacama Compact Array (ACA) for 31 H i detected galaxies in the IC 1459 and NGC 4636 groups. This is the first CO imaging survey for loose galaxy groups. We obtained well-resolved CO data (similar to 0.7-1.5 kpc) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the H i and UV data, we probe the impacts of the group environment on the cold gas components (CO and H i gas) and star formation activity. We find that CO and/or H i morphologies are disturbed in our group members, some of which show highly asymmetric CO distributions (e.g., IC 5264, NGC 7421, and NGC 7418). In comparison with isolated galaxies in the xCOLD GASS sample, our group galaxies tend to have low star formation rates and low H-2 gas fractions. Our findings suggest that the group environment can change the distribution of cold gas components, including the molecular gas and star formation properties of galaxies. This is supporting evidence that preprocessing in the group-like environment can play an important role in galaxy evolution.

Original languageEnglish
Article number31
Number of pages35
JournalAstrophysical Journal Supplement Series
Issue number1
Publication statusPublished - 1 Sept 2022


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