Galaxy Groups in the Local Universe: Gas Content and AGN Feedback in a Complete Sample
Abstract
Galaxy groups are arguably the most important environment for our understanding of galaxy evolution, AGN feedback and the development of the hot intergalactic medium (IGM). Groups are a diverse class, ranging from cold-gas-rich assemblages of star-forming galaxies to more massive elliptical-dominated systems with extensive X-ray halos. I will discuss results from the Complete Local-volume Groups Sample (CLoGS), an optically-selected statistically-complete sample of 53 groups in the nearby Universe (D<80 Mpc). CLoGS has been surveyed in the X-ray (XMM-Newton and/or Chandra) and low-frequency radio bands (GMRT 235 & 610 MHz) and, for the dominant galaxies, in molecular gas (IRAM 30m or APEX CO). With supporting data on ionized and atomic gas for a subset of systems, the sample provides insight into the relationship between the group environment and the dominant galaxy, the range in properties across the group population, and the AGN feedback cycle. We find that about half our groups are X-ray luminous systems, with about one third of those showing signs of dynamical interactions (mergers or sloshing) and one third affected by recent AGN outbursts. Roughly 40% of our group-dominant galaxies are detected in CO, and around half have HI, but connection between AGN, cold gas, hot IGM is not as straightforward as in galaxy clusters and there is evidence that the galaxies richest in cold gas may have acquired it through galaxy interactions or mergers. I will describe the conditions under which feedback occurs and its impact on groups, and note some cases that may be challenging for current feedback models.
- Publication:
-
Multiphase AGN Feeding & Feedback II
- Pub Date:
- June 2022
- Bibcode:
- 2022maff.confE..42O