STRUCTURE FORMATION IN A UNIVERSE WITH COLD PLUS HOT DARK MATTER

We examine the effect of a small admixture of hot dark matter (HDM) to the "standard" cold dark matter (CDM) model for galaxy formation. With equal amounts of HDM and CDM, the growth of galactic scale density peaks in the CDM component is highly damped and galaxy formation is problematic, as has been discussed elsewhere. However, if the HDM contribution is less than or similar to 30% then the damping is not so severe and galaxies can still form by a reasonable redshift. Further, with this amount of HDM, agreement with large-scale structure observations are greatly improved over that of pure CDM. In this paper we demonstrate this by comparing the predictions of CDM and cold plus hot dark matter (CPHDM) models with the most recent observations. We will consider galactic cluster correlations, large-scale peculiar velocity flows, observationally derived power spectra, and the likelihood of finding a Great Attractor-sized object. Galaxy formation is still a computationally subtle issue, but we make some preliminary observations concerning two-point correlations and formation times.