Quantifying the coherent outflows of galaxies around voids in the SDSS DR7

Abstract

We report the detection, with a high level of confidence, of coherent outflows around voids found in the seventh data release of the Sloan Digital Sky Survey (SDSS DR7). In particular, we developed a robust <|cos theta|> statistical test to quantify the strength of redshift-space distortions (RSD) associated with extended coherent velocity fields. We consistently find that the vector that joins void centers with galaxies that lie in shells around them is more likely to be perpendicular to the line-of-sight than parallel to it. This effect is clear evidence for the existence of outflows in the vicinity of voids. We show that the RSD exist for a wide range of void radius and shell thickness, but they are more evident in the largest voids in our sample. For instance, we find that the <|cos theta|> for galaxies located in shells within 2 h^-1 Mpc from the edge of voids larger than 15 h^-1 Mpc deviates 3.81sigma from uniformity. The measurements presented in this work provide useful information to constrain cosmological parameters, in particular Omega_m and Sigma_8.

4 pages, 1 figure, to appear in A&A Letters

References in corpus (4)

• A test of the nature of cosmic acceleration using galaxy redshift distortions
• Testing cosmological structure formation using redshift-space distortions
• Large-Scale Anisotropic Correlation Function of SDSS Luminous Red Galaxies
• Spin alignment of dark matter haloes in the shells of the largest voids

Cited by in corpus (10)

• A public void catalog from the SDSS DR7 Galaxy Redshift Surveys based on the watershed transform
• The nonlinear matter and velocity power spectra in f(R) gravity
• Clues on void evolution II: Measuring density and velocity profiles on SDSS galaxy redshift space distortions
• Photometric Properties of Void Galaxies in the Sloan Digital Sky Survey DR7 Data Release
• Real-space density profile reconstruction of stacked voids
• Clues on void evolution III: Structure and dynamics in void shells
• Alcock-Paczynski cosmological test
• The structure of cosmic voids in a LCDM Universe
• Void replenishment: how voids accrete matter over cosmic history
• Constraining cosmological parameters using void statistics from the SDSS survey