The prevalence of repeating fast radio bursts

Understand

Fast radio bursts are extragalactic, sub-millisecond radio impulses of unknown origin [1,2].

• Their dispersion measures, which quantify the observed frequency-dependent dispersive delays in terms of free-electron column densities, significantly exceed predictions from models [3] of the Milky Way interstellar medium.
• The excess dispersions are likely accrued as fast radio bursts propagate through their host galaxies, gaseous galactic halos and the intergalactic medium [4,5].
• Despite extensive follow-up observations of the published sample of 72 burst sources [6], only two are observed to repeat [7,8], and it is unknown whether or not the remainder are truly one-off events.