Cosmology with the kinetic Sunyaev-Zeldovich effect: Independent of the optical depth and $\sigma_8$

TL;DR

This paper introduces a new velocity-based statistic for kinetic Sunyaev-Zeldovich data that breaks the optical-depth degeneracy, enabling independent constraints on cosmological parameters like neutrino mass.

Contribution

The authors propose a novel triplet-based velocity statistic that provides cosmological constraints independent of optical depth and $\sigma_8$, demonstrated through simulations.

Findings

Achieves 6.2-12.9 times better constraints on cosmological parameters than previous methods.

Effectively constrains the summed neutrino mass.

Enables parameter estimation solely from kinetic Sunyaev-Zeldovich data.

Abstract

The cosmological constraints from the kinetic Sunyaev-Zeldovich experiments are degenerate with the optical depth measurement, which is commonly known as the optical-depth degeneracy. In this work, we introduce a new statistic based on the first moment of relative velocity between pairs in a triplet, which is capable of constraining cosmological parameters independent of the optical depth, and $\sigma_8$. Using 22,000 $N$-body simulations from the Quijote suite, we quantify the information content in the new statistic using Fisher matrix forecast. We find that it is able to obtain strong constraints on the cosmological parameters, particularly on the summed neutrino mass. The constraints have a factor of 6.2-12.9, and 2.3-5.7 improvement on all cosmological model parameters when compared to those obtained from the mean pairwise velocity, and the redshift-space halo power spectrum, respectively. Thus the new statistic paves a way forward to constrain cosmological parameters independent of the optical depth and $\sigma_8$ using data from future kinetic Sunyaev-Zeldovich experiments alone.