Joint Astrophysics Colloquium

A Unified Picture of Fast Radio Bursts

Wenbin Lu

Caltech

Fast radio bursts (FRBs) are short duration (~ms), very bright, radio transients. Their detection a decade ago was a major unexpected discovery in astronomy in decades. Hunting for FRBs and measuring their physical properties have become one of the leading scientific goals in astronomy. This effort has led to a rapidly growing sample with extremely diverse properties in luminosity (10^38 to 10^45 erg/s), duration (0.1 ms to 10 ms), and repetition rate (some objects have multiple bursts in an hour and many just one burst in a few years). I will present a study of their cosmological volumetric rate density and provide evidence that these bursts all belong to the same class of transients --- most likely all are repeaters. According to my model, disturbances close to the surface of a magnetar launch Alfven waves into the magnetosphere, which propagate to a distance of a few tens of neutron star radii and then produce coherent radio emission. The coincident hard X-rays associated with the Galactic FRB 200428 can be understood in this scenario. This model provides a unified picture for weak Galactic FRBs as well as the bright bursts seen at cosmological distances. If time allows, the polarization properties of FRBs will also be addressed.