Search for the correlations between host properties and ${\rm DM_{host}}$ of fast radio bursts: constraints on the baryon mass fraction in IGM

TL;DR

This study uses 17 localized FRBs to investigate correlations between host galaxy properties and host dispersion measure, constraining the baryon mass fraction in the intergalactic medium with no strong evidence of evolution.

Contribution

It is the first to analyze correlations between ${\rm DM_{host}}$ and host galaxy properties using localized FRBs, providing new constraints on the IGM baryon fraction.

Findings

No strong correlation between ${\rm DM_{host}}$ and host galaxy properties.

Estimated IGM baryon fraction $f_{\rm IGM,0}$ is approximately 0.78 to 0.83.

Limited data prevents detection of redshift evolution of $f_{\rm IGM}$.

Abstract

The application of fast radio bursts (FRBs) as probes to investigate astrophysics and cosmology requires the proper modelling of the dispersion measures of Milky Way (${\rm DM_{MW}}$) and host galaxy (${\rm DM_{host}}$). ${\rm DM_{MW}}$ can be estimated using the Milky Way electron models, such as NE2001 model and YMW16 model. However, ${\rm DM_{host}}$ is hard to model due to limited information on the local environment of FRBs. In this paper, using 17 well-localized FRBs, we search for the possible correlations between ${\rm DM_{host}}$ and the properties of host galaxies, such as the redshift, the stellar mass, the star-formation rate, the age of galaxy, the offset of FRB site from galactic center, and the half-light radius. We find no strong correlation between ${\rm DM_{host}}$ and any of the host property. Assuming that ${\rm DM_{host}}$ is a constant for all host galaxies, we constrain the fraction of baryon mass in the intergalactic medium today to be $f_{\rm IGM,0}=0.78_{-0.19}^{+0.15}$. If we model ${\rm DM_{host}}$ as a log-normal distribution, however, we obtain a larger value, $f_{\rm IGM,0}=0.83_{-0.17}^{+0.12}$. Based on the limited number of FRBs, no strong evidence for the redshift evolution of $f_{\rm IGM}$ is found.