HST permits the study of high–z cluster galaxies in unprecedented detail and offers a unique opportunity to examine the processes driving galaxy formation. As part of our Advanced Camera for Surveys (ACS) intermediate redshift cluster survey, we have observed 8 galaxy clusters with redshift betwen 0.8 and 1.3. At these redshifts, galaxy clusters are still assembling and galaxies are evolving to...

Cluster strong lensing cosmography is a promising probe of the background geometry Universe and several studies have emerged, thanks to increased quality observations using space ground-based telescopes. For first time, we use sample five cluster lenses measure values cosmological parameters combine them with those from classical probes. In order assess degeneracies effectiveness strong-lensing...

We present results from a deep photometric study of the rich galaxy cluster Abell 2218 (z = 0.18) based on archival HST WFPC2 F606W images. These have been used to derive the luminosity function to extremely faint limits (MF606W ≈ −13.2 mag, μ0 ≈ 24.7mag arcsec ) over a wide field of view (1.3 h Mpc). We find the faint-end slope of the luminosity function to vary with environment within the clu...

We have constructed a large, uniform galaxy cluster catalog from the Sloan Digital Sky Survey data. By studying the morphology–cluster-centric-radius relation, we have found two characteristic environments where galaxy morphologies change dramatically, indicating there exist two different physical mechanisms responsible for the cluster galaxy evolution. We also found an unusual population of ga...