Reshma Thomas: Magnetic field switching in a turbulent fast radio burst environment

Fast radio bursts (FRB) are brief, intense cosmic flashes of radio waves from yet unknown sources in galaxies. Polarization studies of FRBs have shown that they can originate in highly magnetized environments. We observed FRB 20190520B for seventeen months and found that its rotation measure has high-magnitude variations, including two sign changes. The FRB source also depolarizes to- ward low radio frequencies. These properties indicate changes, including ori- entation reversals of the parallel component of the integrated magnetic field along the line-of-sight (LOS). This may result from propagation through a turbulent, magnetized screen within a range of 8 AU to 100 pc away from the source. The geometric outcome is consistent with an FRB seen through the wind of a binary companion.