Systematic-free inference of the cosmic matter density field from SDSS3-BOSS data

TL;DR

This paper introduces a Bayesian method to reconstruct the three-dimensional cosmic matter density field from SDSS-III/BOSS galaxy data, effectively removing systematics and validating results through cross-correlation with Planck lensing data.

Contribution

It develops a systematic-free, physically motivated Bayesian inference framework that accounts for observational effects to map cosmic structures from galaxy surveys.

Findings

Successful cross-correlation with Planck lensing confirms systematic-free analysis.

Reconstructed initial conditions show no bias at relevant scales.

Maps reveal residual systematic effects in SDSS-III/BOSS data.

Abstract

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.