Fast Radio Bursts and Interstellar Objects

Fast radio bursts (FRBs) are transient radio events with millisecond-scale durations, and debated origins. Collisions between planetesimals and neutron stars have been proposed as a mechanism to produce FRBs; the planetesimal strength, size and density determine the time duration and energy of the resulting event. One source of planetesimals is the population of interstellar objects (ISOs), free-floating objects expected to be extremely abundant in galaxies across the Universe as products of planetary formation. We explore using the ISO population as a reservoir of planetesimals for FRB production, finding that the expected ISO-neutron star collision rate is comparable with the observed FRB event rate. Using a model linking the properties of planetesimals and the FRBs they produce, we further show that observed FRB durations are consistent with the sizes of known ISOs, and the FRB energy distribution is consistent with the observed size distributions of Solar System planetesimal populations. Finally, we argue that the rate of ISO-neutron star collisions must increase with cosmic time, matching the observed evolution of the FRB rate. Thus, ISO-neutron star collisions are a feasible mechanism for producing FRBs.
Comment: Accepted for publication in ApJ (6 pages, 1 figure 1 table)