The large scale velocity field from the Cosmicflows-4 data

Understand

The reconstruction of the large scale velocity field from the grouped Cosmicflows-4 (CF4) database is presented.

• The lognormal bias of the inferred distances and velocities data is corrected by the Bias Gaussianization correction (BGc) scheme, and the linear density and velocity fields are reconstructed by means of the Wiener filter (WF) and constrained realizations (CRs) algorithm.
• These tools are tested against a suite of random and constrained Cosmicflows-3-like mock data.
• The CF4 data consists of 3 main subsamples - the 6dFGS and the SDSS data - and the `others'.