Program: GS-2005A-Q-27

Detailed studies of nearby galaxies (z<0.05) have shown that galaxies have very complex histories of formation and evolution involving mergers, bursts of star formation, and morphological changes. Even so, the global properties of the galaxies (radii, luminosities, rotation velocities, velocity dispersions, and absorption line strengths) follow a number of very tight (empirical) scaling relations, e.g. the Tully-Fisher relation and the Fundamental Plane. These relations place constraints on models for galaxy evolution. We are carrying out a large project aimed at studying the galaxy evolution over the last half of the age of the Universe, using similar techniques as those used for z~0 galaxies. The project is based on spectroscopy and photometry of galaxies in 15 rich clusters of galaxies with redshifts between 0.15 and 1.0. The present proposal covers the last GMOS spectroscopic and photometric observations for the project: RXJ1347.5-1145 at z=0.45 and RXJ1415.1+3612 at z=1.01. This is a joint proposal (Gemini staff, UK, US, Canada) that uses both GMOS-N and GMOS-S. Observations of RXJ1347.5-1145 will probe the effects of cluster merging, while observations of RXJ1415.1+3612 are important for firmly establishing our challenge to the passive evolution model.