VOID ANALYSIS AS A TEST FOR DARK-MATTER COMPOSITION

We use the void probability function (VPF) to compare the redshift-spa ce galaxy distribution in the Perseus-Pisces redshift survey with arti ficial samples extracted from N-body simulations of standard cold dark matter (CDM) and broken scale invariance (BSI) models. Observational biases of the real data set are reproduced as well. as possible in the simulated samples. Galaxies are identified as residing in peaks of th e evolved density held, and overmerged structures are fragmented into individual galaxies in such a way as to reproduce both the correct lum inosity function and the two-point correlation function (assuming suit able M/L values). Using a similar approach, it was recently shown that the VPF can discriminate between CDM and a cold + hot dark matter (CH DM) model with Omega(cold)/Omega(hot)/Omega(baryon) = 0.6/0.3/0.1. Our main result is that both CDM (as expected from a previous analysis) a nd BSI fit observational data. The robustness of the result is checked against changing the observer's position in the simulations and the g alaxy identification in the evolved density held. Therefore, while the void statistics is sensitive to the passage from CDM to CHDM (differe nt spectrum and different nature of dark matter), it is not to the pas sage from CDM to BSE (different spectrum but same dark matter). On suc h a basis, we conjecture that the distribution of voids could be direc tly sensitive to the nature of dark matter, but scarcely sensitive to the shape of the transfer function.