Neutrino Mass Constraints from kSZ Tomography

TL;DR

This paper forecasts neutrino mass constraints using kSZ tomography with upcoming CMB and large-scale structure surveys, showing modest improvements unless optical depth priors are used, and highlighting future potential.

Contribution

It introduces a detailed forecast of neutrino mass constraints from kSZ tomography, accounting for realistic factors and demonstrating potential improvements with priors and future surveys.

Findings

kSZ tomography improves neutrino mass constraints by a few percent.

Optical depth priors can enhance constraints by over 15%.

Including CMB lensing reduces the impact of kSZ on constraints.

Abstract

We forecast neutrino mass constraints using Stage IV CMB and large-scale structure surveys, focusing on kSZ tomography as an independent probe of the growth of cosmic structure. We take into account several realistic factors, including the kSZ optical depth degeneracy. Our baseline setup consists of CMB S4 temperature and polarization (but not lensing) information, DESI BAO, the LSST galaxy power spectrum, and a Planck like $\tau$ prior, yielding $\sigma(\sum m_\nu) = 32\, \rm{meV}$. Adding kSZ tomography improves this by a few percent, while a kSZ optical depth prior can push this improvement to over $15\%$, giving $\sigma(\sum m_\nu) = 27\, \rm{meV}$. When CMB lensing is included in the baseline setup, kSZ does not further improve neutrino mass constraints. We find promising prospects for a scenario combining futuristic CMB and galaxy surveys.