Towards a multi-tracer neutrino mass measurement with line-intensity mapping

TL;DR

This paper explores how line-intensity mapping, combined with multi-tracer velocity tomography and future surveys, can significantly improve constraints on the sum of neutrino masses, potentially achieving a 5-sigma detection.

Contribution

It introduces a novel multi-tracer approach using LIM and velocity tomography to enhance neutrino mass measurements in cosmology.

Findings

Next-generation LIM can reach 50 meV sensitivity on neutrino mass.

Velocity tomography improves constraints by approximately 4%.

Combined analysis with CMB-S4 and DESI-BAO can detect neutrino mass at 5-sigma significance.

Abstract

Accurately determining neutrino masses is a main objective of contemporary cosmology. Since massive neutrinos affect structure formation and evolution, probes of large scale structure are sensitive to the sum of their masses. In this work, we explore future constraints on $\sum m_\nu$ utilizing line-intensity mapping (LIM) as a promising emerging probe of the density of our Universe, focusing on the fine-structure [CII] line as an example, and compare these constraints with those derived from traditional galaxy surveys. Additionally, we perform a multi-tracer analysis using velocity tomography via the kinetic Sunyaev-Zeldovich and moving lens effects to reconstruct the three-dimensional velocity field. Our forecasts indicate that the next-generation AtLAST detector by itself can achieve $\sigma_{\Sigma m_\nu} \sim 50$ meV sensitivity. Velocity tomography will further improve these constraints by 4%. Incorporating forecasts for CMB-S4 and DESI-BAO in a comprehensive multi-tracer analysis, while setting a prior on the optical depth to reionization $\tau$ derived using 21-cm forecasted observations, to break degeneracies, we find that a $\gtrsim5\sigma$ detection of $\sum m_\nu\!\sim\! 60$ meV, under the normal hierarchy, is within reach with LIM. Even without a $\tau$ prior, our combined forecast reaches $\sigma_{\Sigma m_\nu} \!\sim\! 18$ meV.