Improvement of cosmological constraints with the cross correlation between line-of-sight optical galaxy and FRB dispersion measure

TL;DR

This paper demonstrates that cross-correlating optical galaxy counts with FRB dispersion measures significantly enhances cosmological constraints by over 20%, leveraging large-scale structure as a key factor.

Contribution

It introduces a novel method of using line-of-sight galaxy counts to improve FRB-based cosmological measurements, validated through N-body simulation mocks.

Findings

Cross-correlation improves cosmological constraints by >20%.

Galaxy counts trace electron density effectively.

Method validated with realistic simulations.

Abstract

Fast Radio Bursts (hereafter FRBs) can be used in cosmology by studying the Dispersion Measure (hereafter DM) as a function of redshift. The large scale structure of matter distribution is regarded as a major error budget for such application. Using optical galaxy and dispersion measure mocks built from N-body simulations, we have shown that the galaxy number density can be used as a tracer for large scale electron density and help improve the measurement of DM as a function of redshift. We have shown that, using the line-of-sight galaxy number counts within 1' around the given localized FRB source can help improve the cosmological parameter constraints by more than 20%.