New observations add fuel to fast radio burst debate

UNTIL RECENTLY, there were dozens of ideas for what powers fast radio bursts (FRBs), ultra-bright flashes of radio waves visible from billions of light-years away. But when astronomers found multiple FRB-like bursts coming from a nearby highly magnetic neutron star, or magnetar, the question of FRB origins seemed to be largely settled. However, studies published in the journals Nature and Nature Communications on FRB 20201124A disagree on its origin. Over several months in 2020, Heng Xu (Peking University, China) and colleagues detected 1,863 bursts from the source using the Five-hundred-metre Aperture Spherical radio Telescope (FAST) in China. The FAST data included polarisation, which, to the team's surprise, revealed that the magnetic field and/or the plasma density around the source sometimes changed dramatically over only a few days. Team member Fayin Wang (Nanjing University,…