Expansion and Collapse of Large-scale Voids - Observational insight

LAURA CECCARELLI; DANTE PAZ; MARCELO LARES; NELSON PADILLA; DIEGO G LAMBAS

Cordoba

Encuentro; Friends of friends meeting; 2014

IATE

We find that small voids are more frequently surrounded by overdense shells whereas larger voids tend to have continuously rising profiles. We analyze the dynamics of voids with and without a surrounding overdense shell in the SDSS. We model the void-galaxy cross-correlation function in redshift space to use the redshift-space distortions to obtain the velocity field around voids. Our redshift space distortion studies indicate that large voids with continuously rising profiles are likely to be expanding. Small voids are typically surrounded by an overdense shell, and their redshift space distortions indicate that they are more likely to be collapsing.We obtained the first observational evidence of a twofold population of voids according to their dynamical properties as predicted by theoretical considerations.