2023MNRAS.518..539M

The dispersion measure (DM) of fast radio burst (FRB) encodes important information such as its distance, properties of intervening medium. Based on simulations in the Illustris and IllustrisTNG projects, we analyse the DM of FRBs contributed by the interstellar medium and circumgalactic medium in the hosts, DM_host. We explore two population models - tracing the star formation rate (SFR) and the stellar mass, i.e. young and old progenitors, respectively. The distribution of DM_host shows significant differences at z = 0 between two populations: the stellar mass model exhibits an excess at the low-DM end with respect to the SFR model. The SFR (stellar mass) model has a median value of 179 (63) pc cm^–3 for galaxies with $M_*=10^{8\!-\!13}\, \mathrm{M}_{\odot }$ in the TNG100-1. Galaxies in the Illustris-1 have a much smaller DM_host. The distributions of DM_host deviate from lognormal function for both models. Furthermore, two populations differ moderately in the spatial offset from host galaxy's centre in the stellar mass function of hosts. DM_host increases with the stellar mass of hosts when $M_* < 10^{10.5}\, \mathrm{M}_{\odot }$, and fluctuate at higher mass. At 0 < z < 2, DM_host increases with redshift. The differences in DM_host between two populations declines with increasing redshift. With more localized events available in the future, statistics such as DM_host, the offset from galaxy centre, and the stellar mass function of hosts will be of great helpful to ascertain the origin of FRB. Meanwhile, statistics of DM_host of localized FRB events could help to constrain the baryon physics models in galaxy evolution.