| |
 |
| Paper: |
Galaxy Transformation in Poor Clusters at z≈0.25 |
| Volume: |
240, Gas and Galaxy Evolution: A Conference in Honor of the 20th Anniversary of the VLA |
| Page: |
619 |
| Authors: |
Ziegler, B. L.; Fricke, K. J.; Balogh, M. L.; Bower, R. G.; Gaztelu, A.; Smail, I.; Davies, R. L. |
| Abstract: |
We have undertaken an intensive observational campaign to study the evolutionary status of galaxies in 9 poor clusters at 0.2<z<0.3. This program comprises ground-based optical and near infrared photometry, medium-resolution multi-object spectroscopy, and HST imaging. The clusters have very low X-ray luminosities (<5×1043 erg s-1) and poor optical richness class. They are dominated by passive galaxies with no or little on-going star formation. The fraction of emission-line galaxies in these low-density environments is as low as in rich clusters at similar epochs (fELG<0.25). This indicates that violent mechanisms like merging or ram-pressure stripping involving bursts of star formation can not be the dominant processes in transforming galaxies in clusters. Rather, a smooth gradual decline in star formation activity over a short timescale is favored for newly infalling field galaxies. |
|
|
|
|
|
