Cosmic structure from dark matter

Following a suggestion by Schaeffer and Silk, we attempt to estimate the present distribution of galaxies from the the linear growth of primordial adiabatic fluctuations. The latter are studied in flat Universe models dominated by dark matter, in either one of its three popular varieties - hot, warm, and cold - or some mixture thereof. The mass distributions are derived either from the canonical Press-Schechter (PS) mechanism or from an approximate peak count, within an assumption of high bias. Our theoretical curves are then confronted with those derived from luminosity functions of galaxies and clusters. On the large scales the PS approach seems to give an acceptable agreement with the data for all models, regardless of their chemical composition (i. e. the nature and the abundance of the dark matter components); the approximate peak approach seems instead to represent less closely the observations. On the small scales on the other hand the results are so strongly sensitive to the chemical composition that it is possible to draw some hints about it: the pure warm model is the one which overall fits better the data.