Strip-Mining the Southern Sky: Scratching the Surface

Abstract

Recent advances in techniques for measuring galaxy redshifts have made it possible to gather large samples that reveal the structure in the universe on scales of 100 Mpc or more. Measurement of these properties is especially interesting because the mechanism for forming large structures may connect the fluctuations in the early universe with present observations. In any case, we would like to know the average properties of the Universe, such as the mass density Ω, but no determination of average properties can be reliable unless it encompasses a sufficient volume to average over fluctuations due to large voids and filaments. Conventional Wisdom (Geller and Huchra 1989) indicates that maps of galaxy distributions show inhomogeneities on scales as large as the surveys. While we expect that deeper surveys will reveal a more homogeneous pattern, the scale on which this transition takes place has not yet been reached in any published survey. This contribution reports initial results based on the first 5100 redshifts from a new survey carried out at Las Campanas Observatory in Chile. With a characteristic depth of one billion light years, the data suggest we may at last have surveyed the universe on a scale where the galaxy distribution tends toward homogeneity. The observed galaxies appear to have voids on the scale of 5000 km/s and filaments similar to those seen in the CfA work, but do not reveal obvious larger structures. Perhaps we are beginning to see the end of large scale structure.