Surface Brightness Evolution of Cluster and Field Galaxies

Abstract

Photometric studies of faint galaxy morphology is an economical alternative to kinematic analysis in the pursuit of an understanding of the physical changes taking place in individual galaxies from z~ 1 to the present day. Two-dimensional surface photometry extends the capabilities of classical morphological analysis because it provides not only a galaxy type but also a number of other physically meaningful parameters. Measurements of size, surface brightness, and color, for individual (bulge and disk) components in the field and in clusters at moderate and high redshift has yielded direct evidence of evolution of the galaxy populations. Elliptical galaxies of a given size are found to have surface brightnesses that increases with redshift as ΔM _B ~—z. Disk galaxies have surface brightnesses that evolve by similar amounts. Over the redshift range 0. 2< z < 0.6 where comparisons have been made, no difference between the evolution of cluster and field populations has been detected (for either disk or elliptical galaxies) . This similarity in surface brightness evolution is accompanied by other parallels. In both cluster and field environments, a population of blue galaxies emerges with increasing redshift and an increasing fraction of the population exhibits “peculiar” structure. Thus, the evolutionary processes in cluster and field galaxies are parallel in several important ways. Understanding environmental contributions to galaxy evolution requires the comparison of cluster galaxy properties with those of field galaxies at the same redshift.

Guest User, Canadian Astronomy Data Centre, which is operated by the Dominion Astrophysical Observatory for the National Research Council of Canada’s Herzberg Institute of Astrophysics.