# Testing gravity with galaxy-galaxy lensing and redshift-space distortions using CFHT-Stripe 82, CFHTLenS and BOSS CMASS datasets

## TL;DR

This study combines galaxy-galaxy lensing and redshift-space distortions from multiple datasets to test General Relativity predictions, providing constraints consistent with Planck results and demonstrating the method's effectiveness in reducing uncertainties.

## Contribution

It presents a joint analysis of GGL and RSD using CFHT and BOSS data, including systematic error correction and mock catalogues, advancing tests of gravity with galaxy surveys.

## Key findings

- Measured growth rate f(z=0.57)=0.95±0.23
- Estimated _{
m m}=0.31b10.08
- Found E_G=0.43b10.10, consistent with _G=b10.40

## Abstract

The combination of Galaxy-Galaxy Lensing (GGL) and Redshift Space Distortion of galaxy clustering (RSD) is a privileged technique to test General Relativity predictions, and break degeneracies between the growth rate of structure parameter $f$ and the amplitude of the linear power-spectrum $\sigma_8$. We perform a joint GGL and RSD analysis on 250 sq. degrees using shape catalogues from CFHTLenS and CFHT-Stripe 82, and spectroscopic redshifts from the BOSS CMASS sample. We adjust a model that includes non-linear biasing, RSD and Alcock-Paczynski effects. We find $f(z=0.57) =0.95\pm0.23$, $\sigma_8(z=0.57)=0.55\pm0.07$ and $\Omega_{\rm m} = 0.31\pm0.08$, in agreement with Planck cosmological results 2018. We also estimate the probe of gravity $E_{\rm G} = 0.43\pm0.10$ in agreement with $\Lambda$CDM-GR predictions of $E_{\rm G} = 0.40$. This analysis reveals that RSD efficiently decreases the GGL uncertainty on $\Omega_{\rm m}$ by a factor of 4, and by 30\% on $\sigma_8$. We use an N-body simulation supplemented by an abundance matching prescription for CMASS to build a set of overlapping lensing and clustering mocks. Together with additional spectroscopic data, this helps us to quantify and correct several systematic errors, such as photometric redshifts. We make our mock catalogues available on the Skies and Universe database.