Systematic-free inference of the cosmic matter density field from
  SDSS3-BOSS data
  We perform an analysis of the three-dimensional cosmic matter density field
traced by galaxies of the SDSS-III/BOSS galaxy sample. The systematic-free
nature of this analysis is confirmed by two elements: the successful
cross-correlation with the gravitational lensing observations derived from
Planck 2018 data and the absence of bias at scales $k \simeq 10^{-3}-10^{-2}h$
Mpc$^{-1}$ in the a posteriori power spectrum of recovered initial conditions.
Our analysis builds upon our algorithm for Bayesian Origin Reconstruction from
Galaxies (BORG) and uses a physical model of cosmic structure formation to
infer physically meaningful cosmic structures and their corresponding dynamics
from deep galaxy observations. Our approach accounts for redshift-space
distortions and light-cone effects inherent to deep observations. We also apply
detailed corrections to account for known and unknown foreground
contaminations, selection effects and galaxy biases. We obtain maps of
residual, so far unexplained, systematic effects in the spectroscopic data of
SDSS-III/BOSS. Our results show that unbiased and physically plausible models
of the cosmic large scale structure can be obtained from present and
next-generation galaxy surveys.
