The effects of peculiar velocities on the morphological properties of large-scale structure

TL;DR

This paper investigates how peculiar velocities affect the morphological properties of large-scale structure using Minkowski functionals, revealing their potential to constrain cosmological parameters more effectively than traditional power spectrum analysis.

Contribution

It provides a detailed analysis of Minkowski functionals on both linear and non-linear scales, demonstrating their utility in cosmological parameter estimation and peculiar velocity studies.

Findings

Minkowski functionals capture non-linear information in LSS.

MF constraints on σ8 outperform power spectrum by ~50%.

MFs offer a new avenue for studying peculiar velocity fields.

Abstract

It is known that the large-scale structure (LSS) mapped by a galaxy redshift survey is subject to distortions by galaxies' peculiar velocities. Besides the signatures generated in common N-point statistics, such as the anisotropy in the galaxy 2-point correlation function, the peculiar velocities also induce distinct features in LSS's morphological properties, which are fully described by four Minkowski functionals (MFs), i.e., the volume, surface area, integrated mean curvature and Euler characteristic (or genus). In this work, by using large suite of N-body simulations, we present and analyze these important features in the MFs of LSS on both (quasi-)linear and non-linear scales, with a focus on the latter. We also find the MFs can give competitive constraints on cosmological parameters compared to the power spectrum, probablly due to the non-linear information contained. For galaxy number density similar to the DESI BGS galaxies, the constraint on $\sigma_8$ from the MFs with one smoothing scale can be better by $\sim 50\%$ than from the power spectrum. These findings are important for the cosmological applications of MFs of LSS, and probablly open up a new avenue for studying the peculiar velocity field itself.