M/L, Hα Rotation Curves, and HiGas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters

Abstract

We have conducted a study of optical and H I properties of spiral galaxies (size, luminosity, Hflux distri- bution, circular velocity, H I gas mass) to investigate causes (e.g., nature versus nurture) for variation within the cluster environment. We find H I deficient cluster galaxies to be offset in Fundamental Plane space, with disk scale lengths decreased by a factor of 25%. This may be a relic of early galaxy formation, caused by the disk coalescing out of a smaller, denser halo (e.g., higher concentration index) or by truncation of the hot gas envelope due to the enhanced local density of neighbors, though we cannot completely rule out the effect of the gas stripping process. The spatial extent of Hflux and the B-band radius also decreases, but only in early type spirals, suggesting that gas removal is less efficient w ithin steeper potential wells (or that stripped late type spirals are quickly rendered unrecognizable). We find n o significant trend in stellar mass-to-light ratios or circular velocities with H I gas content, morphological type, or clustercentric radius , for star forming spiral galaxies throughout the clusters. These data support the fin dings of a companion paper that gas stripping pro- motes a rapid truncation of star formation across the disk, a nd could be interpreted as weak support for dark matter domination over baryons in the inner regions of spiral galaxies. Subject headings:galaxies: clusters — galaxies: evolution — galaxies: kinematics and dynamics