91̽»¨

Abstract:

The interstellar object (ISO) population of the Milky Way is a product of its stars. However, what is in fact a complex structure in the solar neighborhood has traditionally in ISO studies been described as smoothly distributed. Using a debiased stellar population derived from the Gaia Data Release 3 stellar sample, we predict that the velocity distribution of ISOs is far more textured than a smooth Gaussian. The moving groups caused by Galactic resonances dominate the distribution. 1I/‘Oumuamua and 2I/Borisov have entirely normal places within these distributions; 1I is within the noncoeval moving group that includes the Matariki (Pleiades) cluster, and 2I within the Coma Berenices moving group. We show that for the composition of planetesimals formed beyond the ice line, these velocity structures also have a chemodynamic component. This variation will be visible on the sky. We predict that this richly textured distribution will be differentiable from smooth Gaussians in samples that are within the expected discovery capacity of the Vera C. Rubin Observatory. Solar neighborhood ISOs will be of all ages and come from a dynamic mix of many different populations of stars, reflecting their origins from all around the Galactic disk.

Abstract:

Fast radio bursts (FRBs) are transient radio events with millisecond-scale durations and debated origins. Collisions between planetesimals and neutron stars (NSs) 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–NS 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–NS collisions must increase with cosmic time, matching the observed evolution of the FRB rate. Thus, ISO–NS collisions are a feasible mechanism for producing FRBs.