Institute for Advanced Study Astrophysics Seminar

Fast radio bursts (FRBs) are short duration (~ms), very bright, radio transients. Their detection in 2007 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. It is now well established that many FRBs are located at a distance of several billion lightyears, and therefore they are the brightest known transients in the universe in the radio band. Using very general arguments, I will show that the radio emission is coherent, the magnetic field strength associated with the source of these events should be 10^{14}Gauss or more. Recently, an FRB was discovered in the Galaxy and it confirmed that at least some FRBs are associated with magnetars. I will describe my recent work that 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 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.