Void Scaling and Void Profiles in CDM Models

摘要

An analysis of voids using cosmological N-body simulations of cold darkmatter models is presented. It employs a robust statistics of voids, that wasrecently applied to discriminate between data from the Las Campanas RedshiftSurvey and different cosmological models. Here we extend the analysis to 3D andshow that typical void sizes D in the simulated galaxy samples obey a linearscaling relation with the mean galaxy separation lambda: D=D_0+nu*lambda. Ithas the same slope nu as in 2D, but with lower absolute void sizes. The scalingrelation is able to discriminate between different cosmologies. For the beststandard LCDM model, the slope of the scaling relation for voids in the darkmatter halos is too steep as compared to the LCRS, with too small void sizesfor well sampled data sets. The scaling relation of voids for dark matter haloswith increasing mass thresholds is even steeper than that for samples ofgalaxy-mass halos where we sparse sample the data. This shows the strongerclustering of more massive halos. Further, we find a correlation of the voidsize to its central and environmental average density. While there is littlesign of an evolution in samples of small DM halos with v_{circ} ~ 90 km/s,voids in halos with circular velocity over 200 km/s are larger at redshift z =3 due to the smaller halo number density. The flow of dark matter from theunderdense to overdense regions in an early established network of large scalestructure is also imprinted in the evolution of the density profiles with arelative density decrease in void centers by 0.18 per redshift unit between z=3and z=0.