Environment and the Cosmic Evolution of Star Formation

We present a mark correlation analysis of the galaxies in the Sloan DigitalSky Survey using weights provided by MOPED. The large size of the samplepermits statistically significant statements about how galaxies with differentmetallicities and star formation histories are spatially correlated. Massiveobjects formed a larger fraction of their stars at higher redshifts and overshorter timescales than did less massive objects (sometimes calleddown-sizing). We find that those galaxies which dominated the cosmic starformation at z~3 are predominantly in clusters today, whereas galaxies whichdominate the star formation at z~0 inhabit substantially lower mass objects inless dense regions today. Hence, our results indicate that star formation andchemical enrichment occured first in the denser regions of the Universe, andmoved to less dense regions at later times.Comment: 4 pages, 4 figures, submitted to ApJ