Review: galactic angular momenta and angular momentum correlations in the cosmological large-scale structure

TL;DR

This review discusses the theory, simulations, and observations of galactic angular momentum acquisition, correlations, and their impact on weak lensing measurements, highlighting the importance of understanding shape alignments in cosmology.

Contribution

It synthesizes linear models, simulations, and observational data to analyze angular momentum correlations and their effects on weak lensing, providing a comprehensive overview of current understanding.

Findings

Angular momentum correlations influence galaxy shape alignments.

Shape alignments can contaminate weak lensing signals.

Methods exist to mitigate spin-induced contamination in surveys.

Abstract

I review the theory of angular momentum acquisition of galaxies by tidal torquing, the resulting angular momentum distribution, the angular momentum correlation function and discuss the implications of angular momentum alignments on weak lensing measurements: Starting from linear models for tidal torquing I summarise perturbative approaches and the results from n-body simulations of cosmic structure formation. Then I continue to discuss the validity of decompositions of the tidal shear and inertia fields, the effects of angular momentum biasing, the applicability of parameterised angular momentum correlation models and the consequences of angular momentum correlations for shape alignments. I compile the result of observations of shape alignments in recent galaxy surveys as well as in n-body simulations. Finally, I review the contamination of weak lensing surveys by spin-induced shape alignments and methods for suppressing this contamination.