5 research outputs found
Morphological Transformations of Galaxies in the A901/02 Supercluster from STAGES
We present a study of galaxies in the Abell 901/902 Supercluster at z~0.165,
based on HST ACS F606W, COMBO-17, Spitzer 24um, XMM-Newton X-ray, and
gravitational lensing maps, as part of the STAGES survey. We characterize
galaxies with strong externally-triggered morphological distortions and normal
relatively undisturbed galaxies, using visual classification and quantitative
CAS parameters. We compare normal and distorted galaxies in terms of their
frequency, distribution within the cluster, star formation properties, and
relationship to dark matter (DM) or surface mass density, and intra-cluster
medium (ICM) density. We revisit the morphology density relation, which
postulates a higher fraction of early type galaxies in dense environments, by
considering separately galaxies with a low bulge-to-disk (B/D) ratio and a low
gas content as these two parameters may not be correlated in clusters. We
report here on our preliminary analysis.Comment: To appear in the ASP conference proceedings of the "Frank N. Bash
Symposium 2007: New Horizons in Astronomy", Eds. A. Frebel, J. Maund, J.
Shen, M. Siegel. 4 pages, 4 figure
Quantitative measure of evolution of bright cluster galaxies at moderate redshifts
Using archival data from the Hubble Space Telescope, we study the
quantitative morphological evolution of spectroscopically confirmed bright
galaxies in the core regions of nine clusters ranging in redshift from to . We use morphological parameters derived from two
dimensional bulge-disk decomposition to study the evolution. We find an
increase in the mean bulge-to-total luminosity ratio as the Universe
evolves. We also find a corresponding increase in the fraction of early type
galaxies and in the mean S\'ersic index. We discuss these results and their
implications to physical mechanisms for evolution of galaxy morphology.Comment: 5 pages, 3 figures, Accepted for publication in MNRAS: Letter