Large Scale Velocity Fields Present and Future: Making Sense of the data

Abstract

The large scale velocity field was sampled recently by two independent methods: the supernovae type Ia light curve shapes (Riess, Press \& Kirshner) and the Abell Cluster Catalog brightest cluster galaxy metric luminosity (Lauer \& Postman). The results of these investigations seem to be contradictory. I present an analysis of these samples, compare them and investigate whether standard structure formation models and other deep surveys are compatible with them. I also make suggestions as to how to improve the samples so we can actually resolve the bulk flow vectors. I show that although these two samples seem to cover the same volume, their window functions are sufficiently different so that they are only weakly correlated. Further, since both samples are sparse, they are noise dominated and in order to improve the signal to noise they need to either increase their sample size (RPK) or decrease the measurement errors (LP) significantly.