Scintillation timescale measurement of the highly active FRB20201124A

Understand

Scintillation of compact radio sources results from the interference between images caused by multipath propagation, and probes the intervening scattering plasma and the velocities of the emitting source and scattering screen.

• In FRB20201124A, a repeating fast radio burst (FRB) which entered a period of extreme activity, we obtained many burst detections in observations at the upgraded Giant Metrewave Radio Telescope (uGMRT) and the Effelsberg 100\,m Radio Telescope.
• Bursts nearby in time show similar scintillation patterns, and we measure a scintillation timescale of $14.3\pm1.2$\,min and $7\pm2$\,min at Effelsberg (1370\,MHz) and uGMRT (650\,MHz), respectively, by correlating burst pair spectra.
• The scintillation bandwidth scaled to 1\,GHz is $0.5\pm0.1$\,MHz, and the inferred scintillation velocity at Effelsberg is $V_{\mathrm{ISS}}\approx (59\pm7) \sqrt{d_{l}/2\,\rm{kpc}}~{\rm km~s}^{-1}$, higher than Earth's velocity for any screen beyond a lens distance of $d_{l} \gtrsim 400\,$pc.