# Multipole analysis of redshift-space distortions around cosmic voids

## TL;DR

This study analyzes redshift-space distortions around cosmic voids using SDSS data, accurately modeling the data with linear theory, constraining the growth rate of structure, and finding a mild deviation from model expectations at lower redshifts.

## Contribution

It demonstrates that linear theory suffices for modeling void-based redshift-space distortions and provides competitive constraints on the growth rate of structure.

## Key findings

- Linear theory accurately describes the data across scales.
- Constraints on the growth rate are competitive with galaxy clustering results.
- A mild deviation from model expectations is observed at low redshift.

## Abstract

We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about $2h^{-1}{\rm Mpc}$. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter $\beta$ at two median redshifts, $\beta(\bar{z}=0.32)=0.599^{+0.134}_{-0.124}$ and $\beta(\bar{z}=0.54)=0.457^{+0.056}_{-0.054}$, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild $2\sigma$ deviation at $\bar{z}=0.32$, which increases to $3\sigma$ when the data is restricted to the lowest available redshift range of $0.15<z<0.33$.