An estimation of the Local growth rate from Cosmicflows-3 peculiar velocities

Abstract

This article explores three usual estimators, noted as $v_{12}$ of the pairwise velocity, $\ddot{I}{ˆ}_1$ and $\ddot{I}{ˆ}_2$ of the observed two-point galaxy peculiar velocity correlation functions. These estimators are tested on mock samples of {\it Cosmicflows-3} dataset \citep{Tully:2016aa} , derived from a numerical cosmological simulation, and also on a number of constrained realizations of this dataset. Observational measurements errors and cosmic variance are taken into consideration in the study. The result is a local measurement of $f\ddot{I}{ƒ}_8=0.43{\left(\pm 0.03\right)}_{\mathrm{obs}}{\left(\pm 0.11\right)}_{\mathrm{cosmic}}$ out to $z=0.05$, in support of a $\hat{I}›$CDM cosmology.

9 pages, 7 figures, submitted since Feb 9 2018 to MNRAS, currently under fourth revision