Kinematic lensing with high-resolution spectroscopic surveys. A unique opportunity for transformative cosmology at high redshifts in the 2040s

TL;DR

This paper advocates for high-redshift cosmic shear surveys using kinematic lensing with next-generation spectroscopic instruments, promising significantly improved signal-to-noise ratios at redshifts 2-5, enabling transformative cosmological insights.

Contribution

It introduces the novel technique of kinematic lensing for high-redshift shear measurements and demonstrates its potential to outperform current weak lensing surveys in signal quality.

Findings

KL signal-to-noise ratio is twice that of Euclid or LSST at high redshifts.

KL enables cosmic shear measurements at redshifts 2-5.

Potential to probe structure growth during matter and dark energy domination.

Abstract

We present a science case to perform high-redshift cosmic shear surveys for cosmology with next-generation spectroscopic instruments, such as the proposed MegaMapper and Wide-field Spectroscopic Telescope. We argue that by using the novel technique called 'kinematic lensing' (KL) it will be possible to obtain shear catalogues at redshifts between 2 and 5. We show that the signal-to-noise ratio of KL at such high redshifts is on average twice as much that expected from current weak lensing (WL) surveys such as Euclid or LSST, and several times that of the previous generation of WL surveys like DES and KiDS, even with very conservative assumptions about the fraction of spectroscopically-detected sources for which KL shear estimates will be available. This will allow cosmologists to perform joint galaxy clustering-cosmic shear analyses over unprecedented cosmic volumes and to probe the growth of structures deep in the matter-dominated era and across the onset of dark-energy domination, offering a unique opportunity to unveil the mystery of cosmic acceleration.