Lagrangian space remapping and the angular momentum reconstruction from cosmic structures

TL;DR

This paper evaluates the accuracy of remapping galaxy and cluster positions to their initial Lagrangian coordinates and explores how this affects the reconstruction of their angular momentum, providing insights into primordial perturbations.

Contribution

It demonstrates the effectiveness of numerical simulations and advanced reconstruction techniques in accurately remapping structures and analyzing their angular momentum, highlighting the potential for improved primordial perturbation studies.

Findings

Galaxy groups and clusters with mass > 10^{13} M_sun} can be accurately remapped.

Errors in remapping and redshift distortions are subdominant in angular momentum estimation.

Reconstructed initial gravitational potential dominates spin reconstruction errors.

Abstract

Large scale structures provide valuable information of the primordial perturbations that encode the secrets of the origin of the Universe. It is an essential step to map between observables and their initial coordinates, called Lagrangian space, from which primordial perturbations transfer their information to structures via linear theory. By using numerical simulations and state-of-the-art reconstruction techniques, we report the accuracy of estimating the Lagrangian coordinates of galaxies and galaxy clusters, represented by dark matter halos in various ranges of mass, and study the accuracy of this remapping on the angular momentum (spin) reconstruction. Our work shows that galaxy groups and clusters, represented by halos with mass $\gtrsim 10^{13}M_\odot$, can be accurately remapped to Lagrangian space, and their spin reconstruction errors are dominated by the reconstructed initial gravitational potential. For all mass ranges, the errors of Lagrangian remapping, as well as redshift space distortions, play subdominant roles in estimating their angular momenta. This study explains the low correlation level between observed galaxy spins and reconstructed cosmic initial conditions and illustrates the potential of using angular momenta of cosmic structures to improve the reconstruction of primordial perturbations.