The small-scale clustering properties of dwarf galaxies
J. Patricia Vader, Allan Sandage · The Astrophysical Journal · 1991
We report two results on the small-scale clustering properties of dwarf galaxies identified in the vicinity of early-type Shapley-Ames galaxies on high-resolution photographic plates. 1. Dwarf galaxies display the same trend of stronger clustering toward earlier morphological type on small scales as their giant counterparts on larger scales. Early-type dwarfs have a surface density as a function of projected radial distance R from E-E/S0 galaxies of the form {SIGMA}(R) is proportional to R^-1.22+/-0.05^ for 25 gamma with γ= 2.22 and r_0_ = 10 Mpc. The steepness of γ and the tendency of early-type dwarf galaxies to be satellites of giant galaxies suggest that early-type dwarf galaxies are the most strongly clustered of all galaxies. Our results indicate that early-type dwarfs can be used as dynamical probes of dark halos around early-type giant galaxies and as tracers of the dynamical evolution of such halos in dense environments. 2. The trend of increasing early-type dwarf frequency per early-type giant with environment richness previously established for rich groups is found to be continued in the less rich environments studied here. Our data cover a range in early-type dwarf to giant ratio of a factor of 20. We find a minimum value of ~0.25 for isolated early-type galaxies, as compared to a maximum of ~8 previously found in rich environments like the Virgo Cluster.