Cosmic tidal reconstruction in redshift space

TL;DR

This paper demonstrates the application of tidal reconstruction to simulated galaxies in redshift space, showing high-fidelity transverse mode reconstruction and potential for cosmic variance reduction in future surveys.

Contribution

It extends tidal reconstruction methods to redshift space galaxy simulations, analyzing anisotropic effects and the fidelity of reconstructed large-scale modes.

Findings

Transverse modes are reconstructed with high fidelity.

Radial modes are noisier due to velocity dispersion.

Reconstructed tides field is an ideal tracer for cosmic variance cancellation.

Abstract

The gravitational coupling between large- and small-scale density perturbations leads to anisotropic distortions to the local small-scale matter fluctuations. Such local anisotropic distortions can be used to reconstruct the large-scale matter distribution, known as tidal reconstruction. In this paper, we apply the tidal reconstruction methods to simulated galaxies in redshift space. We find that redshift-space distortions lead to anisotropic reconstruction results. While the reconstructed radial modes are more noisy mainly due to the small-scale velocity dispersion, the transverse modes are still reconstructed with high fidelity, well correlated with the original large-scale density modes. The bias of the reconstructed field at large scales shows a simple angular dependence which can be described by a form similar to the linear redshift-space distortion. The noise power spectrum is nearly isotropic and scale-independent on large scales. This makes the reconstructed tides field an ideal tracer for cosmic variance cancellation and multi-tracer analysis and has profound implications for future 21~cm intensity mapping surveys.