Probing the anisotropic distribution of baryon matter in the Universe using fast radio bursts

TL;DR

This paper explores using fast radio bursts (FRBs) to detect large-scale anisotropies in baryon matter distribution, showing that hundreds to thousands of FRBs are needed depending on the anisotropy strength.

Contribution

It demonstrates the feasibility of using FRBs as probes for cosmic baryon anisotropy and quantifies the number of FRBs required for detection at different confidence levels.

Findings

400 FRBs can detect anisotropy with 95% confidence if dipole amplitude is ~0.01

1000 FRBs are insufficient to precisely determine the dipole direction within 40°

Uncertainty in host galaxy dispersion measure has minimal impact on results.

Abstract

We propose that fast radio bursts (FRBs) can be used as the probes to constrain the possible anisotropic distribution of baryon matter in the Universe. Monte Carlo simulations show that, 400 (800) FRBs are enough to detect the anisotropy at 95\% (99\%) confidence level, if the dipole amplitude is at the order of magnitude 0.01. However, much more FRBs are required to tightly constrain the dipole direction. Even 1000 FRBs are far from enough to constrain the dipole direction within angular uncertainty $\Delta\theta<40^{\circ}$ at 95\% confidence level. The uncertainty on the dispersion measure of host galaxy does not significantly affect the results. If the dipole amplitude is in the level of 0.001, however, 1000 FRBs are not enough to correctly detect the anisotropic signal.