Determine the physical model of galaxy intrinsic alignments

Determine the exact physical model of galaxy intrinsic alignments in the Universe, including sufficient flexibility to capture the effects observed in different hydrodynamical simulations.

Background

The paper models galaxy intrinsic alignments using the nonlinear linear alignment (NLA) model with a fixed amplitude parameter, A_IA = 1.0. The authors emphasize that this simplified effective model does not include several potentially important physical effects, such as galaxy–halo misalignments, morphology-dependent alignments, galaxy formation processes, active galactic nucleus feedback, and baryon-impacted alignment mechanisms.

Because the impact of intrinsic alignments on non-Gaussian weak-lensing statistics depends strongly on the underlying physical alignment model, determining the actual physical model and developing sufficiently flexible treatments is important for reliable cosmological and modified-gravity inference from future weak-lensing surveys.