Presentation #226.01 in the session Pulsars and Radio Transients.
Fast radio bursts are brief, intense flashes of radio waves that arise from unknown sources in galaxies across the universe. Observations of the polarization properties in repeating fast radio bursts have shown they can reside in highly magnetized environments, such as in the immediate vicinity of a recent supernova or massive black hole. We have observed the actively repeating FRB 20190520B over a span of fourteen months and found that its Faraday rotation measure is both large in magnitude and rapidly varying.The FRB also depolarizes rapidly at lower frequencies. These phenomena can be explained in terms of multi-path propagation through a highly turbulent, dense magnetized screen. We put strong constraints on the distance to such a screen and narrows down the possible physical configurations that could give rise to the emission seen in FRB 20190520B.