Nonlinear reconstruction of redshift space distortions

TL;DR

This paper demonstrates a nonlinear reconstruction method that significantly enhances the recovery of initial cosmological conditions from redshift space data, improving the number of usable modes and potential for cosmological measurements.

Contribution

The authors introduce a nonlinear reconstruction technique for redshift space distortions that extends the scale of linear mode recovery and enhances cosmological information extraction.

Findings

Number of linear modes increased by a factor of 30-40 after reconstruction.

Reconstruction correlates the anisotropic field with initial conditions at smaller scales.

Method improves cosmological measurements for various large-scale structure surveys.

Abstract

We apply nonlinear reconstruction to the dark matter density field in redshift space and solve for the nonlinear mapping from the initial Lagrangian position to the final redshift space position. The reconstructed anisotropic field inferred from the nonlinear displacement correlates with the linear initial conditions to much smaller scales than the redshift space density field. The number of linear modes in the density field is improved by a factor of 30-40 after reconstruction. We thus expect this reconstruction approach to substantially expand the cosmological information including baryon acoustic oscillations and redshift space distortions for dense low-redshift large scale structure surveys including for example SDSS main sample, DESI BGS, and 21 cm intensity mapping surveys.