Oral Presentation

An ACA CO survey of the IC 1459 group and the NGC 4636 group: environmental effects on molecular gas of group galaxies

Author(s): Bumhyun Lee (Korea Astronomy and Space Science Institute)

Presenter: Bumhyun Lee (Korea Astronomy and Space Science Institute)

We present the results of a 12CO (1-0) imaging survey using the Atacama Compact Array (ACA) for 31 HI-detected galaxies in the IC 1459 group and the NGC 4636 group. This is the first CO imaging survey for loose galaxy groups. We obtained high-resolution CO data (~12 arcsec) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the HI and UV data, we probe the impacts of the group environment on the cold gas components (CO gas and HI gas) and star formation activity. We find that HI and/or CO morphologies are disturbed in our group members, some of which show highly asymmetric CO distributions (e.g., IC 5264 and NGC 7421). In comparison with isolated galaxies in the xCOLDGASS sample, our group galaxies tend to have low star formation rates and low H2 gas fractions. Our findings suggest that the group environment can change the distributions of cold ISM components, including the molecular gas, and star formation properties of galaxies. This is supportive evidence that pre-processing in groups can play an important role in galaxy evolution.