Calibrating $\rm{DM_{IGM}}-z$ relation using host galaxies of FRBs

TL;DR

This paper develops a method to calibrate the $ m{DM_{IGM}}$-redshift relation for FRBs by correlating host galaxy properties with excess dispersion measure, improving cosmological measurements.

Contribution

It introduces a new calibration technique using host galaxy parameters, especially sSFR, to better estimate $ m{DM_{host}}$ and refine the $ m{DM_{IGM}}$-z relation.

Findings

A tight correlation between $ m{DM_{exc}}$ and sSFR was identified.

The calibration method significantly improves the accuracy of $ m{DM_{IGM}}$-z relation.

Host galaxy properties can effectively estimate $ m{DM_{host}}$ for cosmological use.

Abstract

Fast radio bursts (FRBs) are extragalactic radio transients that offer valuable insight of intergalactic medium (IGM). However, the dispersion measure (DM) contributed by IGM ($\rm{DM_{IGM}}$) is degenerated with that from the host galaxy ($\rm{DM_{host}}$), necessitating calibration of the $\rm{DM_{IGM}}$$-z$ relation for cosmological applications. As $\rm{DM_{host}}$ is expected to correlate with host galaxy properties, it is feasible to estimate $\rm{DM_{host}}$ from observable host characteristics. In this study, we conduct spectral energy distribution (SED) and S\'ersic model fittings to derive the parameters of FRB host galaxies. Then, we examine the correlations between the excess dispersion measure ($\rm{DM_{exc}}$) and host galaxy parameters, including star formation rate (SFR), stellar mass, specific star formation rate (sSFR), inclination angle, and projected area. A tight correlation between $\rm{DM_{exc}}$ and sSFR is found. This correlation is utilized to estimate the $\rm{DM_{host}}$ of FRBs, providing a method to calibrate the DM$_{\rm IGM}-z$ relation. This approach leads to a notable improvement in calibration performance.