A dynamical-mass survey of nearby clusters of galaxies

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The purpose of this study was to make a multislit spectrograph and to measure recession velocities of galaxies in nearby clusters to derive the gravitational masses of those clusters. We made the spectrograph in 1997 and verified its performance. We also developed software to measure redshifts from spectral data. Orginally, we planned to carry out observations in 1997. However, since we could not obtain observing times of appropriate, 1-m class telescopes, we did no observations. Instead, on the basis of our available data, we did the follwing studies.1. We developed a program to automatically find clusters from imaging data of galaxies. We also verified its performance using real data.2. We studied the properties of dwarf galaxies in the Coma Cluster, and found that the photometric properties of Coma dwarfs resemble those of dwarf galaxies in the Vorgo Cluster, which is (in contrast with Coma) an irregular and poor luster. This fact suggests that the properties of dwarf galaxies may be universal irrespective of environments.3. We derived the galaxy luminosity functions (LF) for nearby 10 clusters on the basis of our wide-field photometric data. We found that though the shapes of LFs vary among clusters, the shape averaged over the ten clusters is consistant with the shape of LF of field galaxies. We also found that the shapes of type-dependent LFs are universal among clusters.