# Cosmology with kSZ: breaking the optical depth degeneracy with Fast Radio Bursts

## TL;DR

This paper demonstrates that fast radio bursts can effectively break the optical depth degeneracy in kSZ measurements, enabling more precise cosmological constraints from upcoming CMB experiments.

## Contribution

It introduces a novel method using FRBs to resolve the optical depth degeneracy in kSZ measurements, enhancing the potential of CMB-based cosmology.

## Key findings

- FRBs can break the optical depth degeneracy in kSZ measurements
- Enhanced cosmological constraints from upcoming CMB experiments
- New applications of FRBs in cosmology

## Abstract

The small-scale cosmic microwave background (CMB) is dominated by anisotropies from the kinematic Sunyaev-Zeldovich (kSZ) effect, and upcoming experiments will measure it very precisely, but the optical depth degeneracy limits the cosmological information that can be extracted. At the same time, fast radio bursts (FRBs) are an exciting new frontier for astrophysics, but their usefulness as cosmological probes is currently unclear. We show that FRBs are uniquely suited for breaking the kSZ optical depth degeneracy. This opens up new possibilities for constraining cosmology with the kSZ effect, and new cosmological applications for FRBs.