Clues on void evolution I: Large scale galaxy distributions around voids

摘要

We perform a statistical study focused on void environments. We examinegalaxy density profiles around voids in the SDSS, finding a correlation betweenvoid--centric distance to the shell of maximum density and void radius when amaximum in overdensity exists. We analyze voids with and without a surroundingover-dense shell in the SDSS. We find that small voids are more frequentlysurrounded by over-dense shells whereas the radial galaxy density profile oflarge voids tends to rise smoothly towards the mean galaxy density. We analysethe fraction of voids surrounded by overdense shells finding a continuous trendwith void radius. The differences between voids with and without an overdenseshell around them can be understood in terms of whether the voids are, onaverage, in the process of collapsing or continuing their expansion,respectively, in agreement with previous theoretical expectations. We usenumerical simulations coupled to semi-analytic models of galaxy formation inorder to test and interpret our results. The very good agreement between themock catalog results and the observations provides additional support to theviability of a LCDM model to reproduce the large scale structure of theuniverse as defined by the void network, in a way which has not been analysedpreviously.