Using GAMA to probe the impact of small-scale galaxy physics on nonlinear redshift-space distortions

TL;DR

This paper improves models of galaxy redshift-space distortions by incorporating small-scale galaxy physics using halo models and GAMA data, enabling more precise measurements of cosmic structure growth.

Contribution

It introduces a generalized halo model with kinematic biases constrained by GAMA data, enhancing the accuracy of nonlinear RSD modeling at small scales.

Findings

Constraints on satellite galaxy kinematics within haloes

Redshift-space distortions modeled down to 10 kpc scales

Potential for improved growth rate measurements from nonlinear scales

Abstract

We present improved modelling of the redshift-space distortions of galaxy clustering that arise from peculiar velocities. We create mock galaxy catalogues in the framework of the halo model, using data from the Bolshoi project. These mock galaxy populations are inserted into the haloes with additional degrees of freedom that govern spatial and kinematical biases of the galaxy populations relative to the dark matter. We explore this generalised halo model with an MCMC algorithm, comparing the predictions to data from the Galaxy And Mass Assembly (GAMA) survey, and thus derive one of the first constraints on the detailed kinematic degrees of freedom for satellite galaxies within haloes. With this approach, the distortions of the redshift-space galaxy autocorrelations can be accounted for down to spatial separations close to 10 kpc, opening the prospect of improved RSD measurements of the perturbation growth rate by the inclusion of data from nonlinear scales.