Plasmoid ejection by Alfven waves and the fast radio bursts from SGR 1935+2154

In April 2020, two fast radio bursts were detected from a galactic magnetar SGR 1935+2154, and they were coincident with an X-ray burst from this magnetar. We show that the following scenario may produce both the X-ray burst and fast radio bursts. When low amplitude Alfven waves from a magnetar quake propagate to the outer magnetosphere, they can become nonlinear and convert to “plasmoids” (closed magnetic loops) that accelerate away from the star, driving blast waves into the magnetar wind. The plasmoid pushes out the magnetospheric field lines, and they gradually reconnect behind the plasmoid. This dissipation process may produce the X-ray burst. Radio bursts can be produced by the synchrotron maser process at the blast wave. In this presentation, I’ll show our numerical simulations (both 2D and 3D) of the scenario and its implications.