# Transverse Velocities with the Moving Lens Effect

## TL;DR

This paper discusses how the moving lens effect, caused by transverse velocities of large-scale structures, can be detected through CMB and galaxy surveys, enabling the inference of cosmic transverse velocities.

## Contribution

It demonstrates that upcoming CMB and galaxy surveys can statistically detect the moving lens effect and reconstruct transverse velocities of large-scale structures.

## Key findings

- Near-future surveys will enable the first detection of the moving lens effect.
- The method allows for the reconstruction of transverse velocities from observational data.
- The approach enhances understanding of cosmic structure dynamics.

## Abstract

Gravitational potentials which change in time induce fluctuations in the observed cosmic microwave background (CMB) temperature. Cosmological structure moving transverse to our line of sight provides a specific example known as the moving lens effect. Here we explore how the observed CMB temperature fluctuations combined with the observed matter over-density can be used to infer the transverse velocity of cosmological structure on large scales. We show that near-future CMB surveys and galaxy surveys will have the statistical power to make a first detection of the moving lens effect, and we discuss applications for the reconstructed transverse velocity.