The Evolution of X-ray Emitting Groups
Abstract
We have undertaken a multiwavelength project to study the relatively unknown properties of groups and poor clusters of galaxies at intermediate redshifts. The full sample includes nine X-ray selected groups with redshifts betweeen 0.2 and 0.6, and our follow up includes observations with XMM, HST, Gemini, and Keck. The X-ray properties of these systems are generally in good agreement with the properties of low-redshift groups. They appear to follow the scaling relations between luminosity, temperature, and velocity dispersion defined by low-redshift groups and clusters. We also find indications of excess entropy in these systems over self-similar predictions out to large radii. However, the properties of the group galaxies, in particular the central galaxies, show them to be less evolved than similar groups at low-redshift. Roughly half of our intermediate-redshift groups do not have a dominant central elliptical galaxy (BGG), and three of the four BGGs contain multiple luminous nuclei indicating recent merging.
- Publication:
-
AAS/High Energy Astrophysics Division #9
- Pub Date:
- September 2006
- Bibcode:
- 2006HEAD....9.1330J