Lunch talk on May. 25, 2026

Plasma Lensing Interpretation of FRB 20201124A Bursts in Late September 2021

Speaker: Xuechun Chen (Beijing City University)

Venue: Video Conference

Time: 12:45 PM, Monday, May. 25, 2026

Abstract: 

Fast radio bursts (FRBs) are bright millisecond radio transients of extragalactic origin, and the observed properties can be affected by propagation effects. One important effect is plasma lensing, which can significantly magnify the observed flux at certain frequencies, or suppress it when the source is aligned with the lens. We propose that a dramatic increase in burst activity followed by a sudden quenching of FRB 20201124A in September 2021 can be naturally explained with plasma lensing. Using a one-dimensional Gaussian lens model, we search for characteristic spectral peaks in bursts detected before the quenching. We identify several bursts showing stable double-peaked spectral structures and give some constraints on the lens properties from both the frequency-domain and time-domain behaviors.