Model-independent constraints on clustering and growth of cosmic
  structures from BOSS DR12 galaxies in harmonic space
  We present a new, model-independent measurement of the clustering amplitude
of galaxies and the growth of cosmic large-scale structures from the Baryon
Oscillation Spectroscopic Survey (BOSS) 12th data release (DR12). This is
achieved by generalising harmonic-space power spectra for galaxy clustering to
measure separately the magnitudes of the density and of the redshift-space
distortion terms, which are respectively related to the clustering amplitude,
$b\sigma_8(z)$, and the growth, $f\sigma_8(z)$. We adopt a tomographic approach
with 15 redshift bins in the range $z\in[0.15,0.67]$. We restrict our analysis
to strictly linear scales, implementing a redshift-dependent maximum multipole
for each of the tomographic bins. Thus, we obtain 30 data points in total, 15
for each of the quantities $b\sigma_8(z)$ and $f\sigma_8(z)$. The measurements
do not appear to suffer from any apparent systematic effect and show excellent
agreement with the theoretical prediction from a concordance cosmology as from
the Planck satellite. Our results also agree with previous analyses by the BOSS
collaboration. Although each single datum has, in general, a larger error bar
than that obtained in configuration- or Fourier-space analyses, our study
provides the community with a larger number of tomographic data points that
allow for a complementary tracking in redshift of the evolution of fundamental
cosmological quantities.
