Shape of the Galactic Orbits in the CNOC1 Clusters

Abstract

We present an analysis of the orbital properties in 9 intermediate-redshifts cluster of the CNOC1 survey and we compare them to a control sample of 12 nearby clusters. Similar to the nearby elliptical galaxies, the bulge-dominated galaxies in clusters at redshifts ~0.1-0.4 present orbits that are more eccentric than those for disk-dominated galaxies. However, the orbital segregation is less significant than that found for elliptical and spiral galaxies in nearby cluster. When galaxies are separated by colors - red galaxies with colors in the rest frame (U-V)_o > 1.4, and blue galaxies with (U-V)_o =< 1.4 - the strongest orbital segregation is found. Therefore, the segregation we found seems to modify more efficiently the star formation activity than the internal shape of the galaxies. When we compare the orbits of early-type galaxies at intermediate-redshift with those for z=0, they seem to develop significant changes getting much more eccentric. A different behavior is observed in the late-type galaxies, which present no-significant evolution in their orbit shapes.