Internal Kinematics of Spiral Galaxies in Distant Clusters

We introduce our project on galaxy evolution in the environment of richclusters aiming at disentangling the importance of specific interaction andgalaxy transformation processes from the hierarchical evolution of galaxies inthe field. Emphasis is laid on the examination of the internal kinematics ofdisk galaxies through spatially resolved MOS spectroscopy with FORS at the VLT.First results are presented for the clusters MS1008.1-1224 (z=0.30),Cl0303+1706 (z=0.42), and Cl0413-6559 (F1557.19TC) (z=0.51). Out of 30 clustermembers with emission-lines, 13 galaxies exhibit a rotation curve of theuniversal form rising in the inner region and passing over into a flat part.The other members have either intrinsically peculiar kinematics (4), or toostrong geometric distortions (9) or too low S/N (4 galaxies) for a reliableclassification of their velocity profiles. The 13 cluster galaxies for which amaximum rotation velocity could be derived are distributed in the Tully--Fisherdiagram very similar to field galaxies from the FORS Deep Field that havecorresponding redshifts and do not show any significant luminosity evolutionwith respect to local samples. The same is true for seven galaxies observed inthe cluster fields that turned out not to be members. The mass-to-light ratiosof the 13 TF cluster spirals cover the same range as the distant fieldpopulation indicating that their stellar populations were not dramaticallychanged by possible clusterspecific interaction phenomena. The cluster memberswith distorted kinematics may be subject to interaction processes but it isimpossible to determine whether these processes also lead to changes in theoverall luminosity of their stellar populations.Comment: accepted by ApJL, 5 pages in emulateapj5-format; comments welcom