The Completed SDSS-IV Extended Baryon Oscillation Spectroscopic Survey:
  Growth rate of structure measurement from cosmic voids
  We present a void clustering analysis in configuration-space using the
completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation
Spectroscopic Survey (eBOSS) DR16 samples. These samples consist of Luminous
Red Galaxies (LRG) combined with the high redshift tail of the SDSS-III Baryon
Oscillation Spectroscopic Survey (BOSS) DR12 CMASS galaxies (called as
LRG+CMASS sample), Emission Line Galaxies (ELG) and quasars (QSO). We build
void catalogues from the three eBOSS DR16 samples using a ZOBOV-based
algorithm, providing 2,814 voids, 1,801 voids and 4,347 voids in the LRG+CMASS,
ELG and QSO samples, respectively, spanning the redshift range $0.6<z<2.2$. We
measure the redshift space distortions (RSD) around voids using the anisotropic
void-galaxy cross-correlation function and we extract the distortion parameter
$\beta$. We test the methodology on realistic simulations before applying it to
the data, and we investigate all our systematic errors on these mocks. We find
$\beta^{\rm LRG}(z=0.74)=0.415\pm0.087$, $\beta^{\rm
ELG}(z=0.85)=0.665\pm0.125$ and $\beta^{\rm QSO}(z=1.48)=0.313\pm0.134$, for
the LRG+CMASS, ELG and QSO sample, respectively. The quoted errors include
systematic and statistical contributions. In order to convert our measurements
in terms of the growth rate $f\sigma_8$, we use consensus values of linear bias
from the eBOSS DR16 companion papers~\citep{eBOSScosmo}, resulting in the
following constraints: $f\sigma_8(z=0.74)=0.50\pm0.11$,
$f\sigma_8(z=0.85)=0.52\pm0.10$ and $f\sigma_8(z=1.48)=0.30\pm0.13$. Our
measurements are consistent with other measurements from eBOSS DR16 using
conventional clustering techniques.
