The Host Galaxies of Fast Radio Bursts Track a Combination of Stellar Mass and Star Formation, Similar to Type Ia Supernovae

We develop a new statistical framework for studying the host galaxies of astrophysical sources that accounts for both redshift evolution and the multivariate nature of the properties of host galaxies. These aspects are critical when dealing with sources that span a wide range of redshifts, and/or with unknown redshift-dependent selection effects. We apply our method to a sample of fast radio burst (FRB) host galaxies as a means of probing the uncertain progenitor(s) of these events. Using our method, we are able to rule out that FRBs track star formation rate (SFR), as would be expected if FRBs are associated exclusively with young neutron stars born via core-collapse supernovae (SNe). Furthermore, we rule out a recently proposed metallicity-dependent model whereby FRBs track SFR only above an oxygen abundance of 12 + log ( O / H ) ∼ 8 . Motivated by the fact that at least one FRB has been localized to a globular cluster (GC), we also investigate the hypothesis that FRB sources track GC mass and explicitly rule out this scenario. Alternatively, we find that a “mixed” model, whereby FRBs track a linear combination of SFR and stellar mass, best explains the data. The preferred parameters of such a mixed model are similar to those inferred for Type Ia SNe and imply a possible connection between the progenitors of these different transients.