Constraining the Baryon Fraction in the Intergalactic Medium with 92 localized Fast Radio Bursts

TL;DR

This study uses 92 localized fast radio bursts to constrain the baryon fraction in the intergalactic medium, finding it to be between 0.8 and 0.9, which supports the hypothesis that most missing baryons are in the diffuse IGM.

Contribution

It provides new constraints on the IGM baryon fraction using a large sample of localized FRBs across different cosmological models.

Findings

$f_ ext{IGM}$ constrained to 0.8-0.9 range

Results consistent across different cosmological models

No significant redshift evolution detected

Abstract

Fast radio bursts (FRBs) are emerging as powerful cosmological probes for constraining the baryon fraction in the intergalactic medium (IGM), offering a promising avenue to address the missing baryon problem. In this paper, we analyze constraints on the IGM baryon fraction ($f_\mathrm{IGM}$) using 92 localized FRBs, incorporating a corrected probability distribution function for the IGM dispersion measure within three different cosmological models. We find that variations in the underlying cosmological model have a negligible impact on the inferred values of $f_\mathrm{IGM}$. While the NE2001 Galactic electron density model yields slightly higher $f_\mathrm{IGM}$ values compared to the YMW16 model, the results are consistent within the 1$\sigma$ confidence level. Additionally, there is no statistically significant evidence for redshift evolution in $f_\mathrm{IGM}$. Our analysis constrains $f_\mathrm{IGM}$ to the range $0.8 \sim 0.9$, providing strong support for the idea in which the majority of the missing baryons reside in the diffuse IGM.