The 6dF Galaxy Survey: cosmological constraints from the velocity power spectrum
Abstract
We present scaledependent measurements of the normalized growth rate of structure fσ_{8}(k, z = 0) using only the peculiar motions of galaxies. We use data from the 6degree Field Galaxy Survey velocity sample together with a newly compiled sample of lowredshift (z < 0.07) Type Ia supernovae. We constrain the growth rate in a series of Δk ∼ 0.03 h Mpc^{1} bins to ∼35 per cent precision, including a measurement on scales >300 h^{1} Mpc, which represents one of the largest scale growth rate measurement to date. We find no evidence for a scaledependence in the growth rate, or any statistically significant variation from the growth rate as predicted by the Planck cosmology. Bringing all the scales together, we determine the normalized growth rate at z = 0 to ∼15 per cent in a manner independent of galaxy bias and in excellent agreement with the constraint from the measurements of redshiftspace distortions from 6degree Field Galaxy Survey. We pay particular attention to systematic errors. We point out that the intrinsic scatter present in Fundamental Plane and TullyFisher relations is only Gaussian in logarithmic distance units; wrongly assuming it is Gaussian in linear (velocity) units can bias cosmological constraints. We also analytically marginalize over zeropoint errors in distance indicators, validate the accuracy of all our constraints using numerical simulations, and demonstrate how to combine different (correlated) velocity surveys using a matrix `hyperparameter' analysis. Current and forthcoming peculiar velocity surveys will allow us to understand in detail the growth of structure in the lowredshift universe, providing strong constraints on the nature of dark energy.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 November 2014
 DOI:
 10.1093/mnras/stu1615
 arXiv:
 arXiv:1404.3799
 Bibcode:
 2014MNRAS.444.3926J
 Keywords:

 surveys;
 cosmological parameters;
 cosmology: observations;
 dark energy;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 23 pages, 14 figures, submitted to MNRAS. v2 is 25 pages, 17 figures, accepted by MNRAS