The Peculiar Velocity of the Local Group in the Direction of the Virgo Cluster

Abstract

The measurement of the amplitude of the Local Group infall velocity towards the Virgo Cluster is a crucial test for the value of the universal density parameter Ωo and the ratio of the universal Hubble constant to its local value. However, a very large discrepancy exists between total infall velocities derived from peculiar velocity field observations and those derived from “scaling” methods using standard candles in the Virgo and Coma clusters. The former have tended to produce high Virgocentric peculiar velocities (350 to 500 km s−1) whilst the latter give much lower values (-70 to 100 km s−1).