Effects of Interaction Induced Activities in Hickson Compact Groups: CO and FIR Study

Preprint
Publisher Website
Google Scholar
Abstract
A study of CO and FIR emission in a distance limited (z<0.03) complete sample of Hickson Compact Group (HCG) galaxies was conducted in order to examine the effects of their unique environment on the ISM and star formation activity. Ubiquitous tidal interactions in these dense groups would predict enhanced activities among the HCG galaxies compared to isolated galaxies. Instead their CO and FIR properties are surprisingly similar to isolated spirals. The CO data for 80 HCG galaxies presented here indicate that the spirals globally show the same H2 content as the isolated comparison sample, although 20% are deficient in CO emission. The CO deficiency appears linked with the group evolution, and gas exhaustion through past star formation and removal of external gas reserve by tidal stripping of the outer HI disk offer a possible explanation. The IRAS data for the entire sample of 161 HCG galaxies were re-analyzed using ADDSCAN/SCANPI, improving the sensitivity by a factor of 3-5 over the existing Point Source Catalog (PSC) and better resolving the contribution from individual galaxies. We find that FIR emission in HCG galaxies is similar to isolated, Virgo cluster, and weakly interacting galaxies. A factor two enhancement in the 25 micr/100 micr flux ratio among the HCG spirals is found, which suggests intense, localized nuclear starburst activity similar to HII galaxies. A number of early-type galaxies in HCGs are detected in CO and FIR, lending further support to the idea that tidal interactions and tidally induced evolution of the groups and member galaxies are important in our sample.

This publication has 0 references indexed in Scilit: