Velocities hasten to tell us about the Universe

TL;DR

Galaxy peculiar velocities, driven by gravity, offer a promising way to probe the universe's structure and test cosmological models, especially as systematic challenges are being addressed.

Contribution

This paper discusses how improved velocity measurements can enhance constraints on cosmological parameters and test theories of gravity.

Findings

Velocity measurements can constrain gravity modifications.

Systematic effects are being mitigated.

Potential for new insights into universe's structure.

Abstract

The peculiar velocities of galaxies are driven by gravity, and hence hold the promise of probing details of how gravity forms structures. In particular it is possible to constrain cosmological parameters and to test extensions to the standard model, such as modifications to the theory of gravity or the existence of primordial density perturbations which are non-Gaussian. This constraining power has been frustrated by systematic effects, but we appear to be entering an era when velocity measurements may finally be living up to their promise.