Calibrating the DM_IGM–<i>z</i> Relation Using Host Galaxy Properties of Fast Radio Bursts

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