We measure the clustering of quasars of the final data release ( DR16 ) of the extended Baryon Oscillation Spectroscopic Survey ( eBOSS ) .
The sample contains 343 708 quasars between redshifts 0.8 \leq z \leq 2.2 and covers 4699 \mathrm { deg } ^ { 2 } .
We calculate the even Legendre multipoles ( up to \ell = 4 ) of the anisotropic power spectrum at the effective redshift z _ { eff } = 1.480 and perform a BAO and a Full-Shape ( FS ) analysis .
For both measurements , the errors quoted are dominated by statistics and include systematic errors that amounts to one third of the statistical error .
The systematic errors comprise a modelling part that is determined using a blind N-Body mock challenge and observational effects that are studied with a set of approximate mocks .
Special care was taken to model the damping of the power spectrum , and to account for various types of redshift smearing as well as accounting for fibre collisions .
For the BAO analysis , we measure the transverse comoving distance D _ { M } ( z _ { eff } ) / r _ { drag } { } = 30.60 \pm { 0.90 } and the Hubble distance D _ { H } ( z _ { eff } ) / r _ { drag } { } = 13.34 \pm { 0.60 } .
This measurement is in agreement with the analysis performed in configuration space and the consensus analysis yields : D _ { M } ( z _ { eff } ) / r _ { drag } { } = 30.69 \pm { 0.80 } and D _ { H } ( z _ { eff } ) / r _ { drag } { } = 13.26 \pm { 0.55 } .
In the FS analysis , we fit the power spectrum in the range k = [ 0.02 , 0.30 ] \mathrm { h } \cdot \mathrm { Mpc } ^ { -1 } { } using a model based on Regularised Perturbation Theory , that includes Redshift Space Distorsions ( RSD ) and the Alcock-Paczynski effect .
The results for this analysis are D _ { M } ( z _ { eff } ) / r _ { drag } { } = 30.68 \pm { 0.90 } and D _ { H } ( z _ { eff } ) / r _ { drag } { } = 13.52 \pm { 0.51 } and we constrain the linear growth rate of structure f ( z _ { eff } ) \sigma _ { 8 } ( z _ { eff } ) { } = 0.476 \pm { 0.047 } .
Our results are in agreement with the configuration space analysis .
The consensus analysis of the eBOSS quasar sample yields : D _ { M } ( z _ { eff } ) / r _ { drag } { } = 30.21 \pm { 0.79 } , D _ { H } ( z _ { eff } ) / r _ { drag } { } = 13.23 \pm { 0.47 } and f ( z _ { eff } ) \sigma _ { 8 } ( z _ { eff } ) { } = 0.462 \pm { 0.045 } and is in agreement with a flat \Lambda { CDM } cosmological model using Planck results .