The VIMOS Public Extragalactic Redshift Survey (VIPERS): The growth of structures at $0.5<z<1.2$ from redshift-space distortions in the clustering of the PDR-2 final sample

TL;DR

This paper measures the growth rate of cosmic structures at redshifts 0.5 to 1.2 using galaxy clustering data from VIPERS, improving modeling of redshift-space distortions and providing results consistent with standard cosmology.

Contribution

The study introduces improved non-linear RSD modeling techniques and robust corrections for VIPERS data, enabling unbiased growth rate measurements at intermediate redshifts.

Findings

Measured growth rate parameters: fσ8=0.55±0.12 at z=0.6 and 0.40±0.11 at z=0.86.

Demonstrated negligible bias in growth rate measurements down to 5h^{-1} Mpc scales.

Results align with predictions of ΛCDM cosmology under Einstein gravity.

Abstract

We present measurements of the growth rate of cosmological structure from the modelling of the anisotropic galaxy clustering measured in the final data release of the VIPERS survey. The analysis is carried out in configuration space and based on measurements of the first two even multipole moments of the anisotropic galaxy auto-correlation function, in two redshift bins spanning the range $0.5 < z < 1.2$. We provide robust and cosmology-independent corrections for the VIPERS angular selection function, allowing recovery of the underlying clustering amplitude at the percent level down to the Mpc scale. We discuss several improvements on the non-linear modelling of redshift-space distortions (RSD) and perform detailed tests of a variety of approaches against a set of realistic VIPERS-like mock realisations. This includes using novel fitting functions to describe the velocity divergence and density power spectra $P_{\theta\theta}$ and $P_{\delta\theta}$ that appear in RSD models. These tests show that we are able to measure the growth rate with negligible bias down to separations of $5h^{-1}Mpc$. Interestingly, the application to real data shows a weaker sensitivity to the details of non-linear RSD corrections compared to mock results. We obtain consistent values for the growth rate times the matter power spectrum normalisation parameter of $f\sigma_8=0.55\pm 0.12$ and $0.40\pm0.11$ at effective redshifts of $z = 0.6$ and $z=0.86$ respectively. These results are in agreement with standard cosmology predictions assuming Einstein gravity in a $\Lambda \rm{CDM}$ background.