Title: Precise constraints on the growth rate from RSD in the void-galaxy cross-correlation
Abstract: The vast increase in depth and data volume from forthcoming LSS surveys allows the use of a new tracer of the matter distribution for cosmology, cosmic voids. Void positions indicate regions of low density in which the dynamics and growth of structure are closer to linear theory. I will describe recent developments in the modelling of redshift-space distortions in the cross-correlation of voids and galaxy positions, and show that a purely linear RSD model provides an excellent fit to the data on all scales. This will allow precise constraints on the environment-dependence of the growth rate of structure with Stage IV LSS survey data, at the level of a few percent. I will describe practical challenges that arise in the measurement of this effect in survey data, and how they can be resolved through the adaptation of the reconstruction technique used for BAO. I will discuss the implications for the development of a sensitive Alcock-Paczynski test of the cosmic expansion history, and tests of modified gravity with density-dependent screening mechanisms.