The clustering of dwarf galaxies

We have studied the spatial distribution of dwarf irregular galaxies in and around a nearby void, as a test of some models of biased galaxy formation. New, deep Palomar Schmidt plates were searched for dwarf candidates in the vicinity of a void centered at α = 0^h^45, δ = +20^deg^, v = 3500 km s^-1^. Velocities of 102 objects were obtained with the Arecibo 305 m telescope. These proved to be typical dwarf irregulars, with average velocity widths of 100 km s^-1^ and absolute B-magnitudes of -16.0 (assuming H_0_ = 100 km s^-1^ Mpc^-1^). The distribution of the dwarfs is qualitatively similar to that of bright galaxies in the region, each set of objects equally well delineating voids and high-density regions. A quantitative analysis confirms this impression: except on small scales, where galaxy interactions may be depleting the numbers of very small dwarfs, the autocorrelation and cross-correlation functions, and the nearest-neighbor distributions of dwarfs and giants, are indistinguishable. We discuss the constraints that this result puts on specific models of biased galaxy formation.