X-Ray Analysis of Point Sources and Diffuse Gas in Hickson Compact Groups
Abstract
In an effort to determine the evolutionary state of Hickson Compact Groups (HCGs), we have performed an analysis of the sixteen HCGs in the Chandra X-Ray Observatory archives. HCGs are dense galactic systems, interacting on short time scales, which are ideal for studying galaxy mergers and interactions. We have analyzed both the diffuse gas emission of the compact groups as well as their associated individual point source populations. The total X-ray gas and total point source luminosities were used to determine the group's state of evolution. It was expected that the point source activity would allow for a clear-cut separation between compact groups in different evolutionary states. The sample groups were sorted into three evolutionary categories. Type-A groups are young systems, displaying a group dominated by spiral galaxies, active star formation, and little intragroup X-ray gas. Type-B groups are characterized by an intermediate X-ray point source population, an increased activity and interaction between group members, and intermediate diffuse gas component. HCG 97 is an example of a type-B system. It contains an intragroup gas medium, and eleven associated point sources. As the system further evolves, we expect to find a greater number of point sources. Type-C systems display an advanced stage of interaction between members, an extensive luminous point source population and a large diffuse gas reservoir. HCG 92, Stephan's Quintet, is the archetypical type-C system; it contains a large intragroup gas halo and twenty-six associated point sources. The archival HCGs investigated display a positive correlation between total point source luminosity and total diffuse gas luminosity. The results suggest X-ray point sources can be used to evaluate the evolutionary state of a group. Further research will probe the connection between fully coalesced compact groups and isolated elliptical galaxies.
- Publication:
-
American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21541020B