Two separate studies examine whether repeating fast radio bursts (FRBs) show periodicity consistent with magnetar spin. One analysis focuses on FRB 20240114A, which is described as extraordinarily active. Using 11,553 detected bursts (including 3,196 on MJD 60381, March 12, 2024), researchers search for peaks in a periodogram across an observing span of 15,628 seconds. They report no significant periodic peak in the data. They argue the time window is short enough that even a characteristic magnetar slowing age of about one year would not significantly smear a periodicity of at least 0.1 seconds during the observation, and they show that artificially imposed modulation with an amplitude of 0.15 would have been robustly detected.
A second paper reports a detection of a near-second periodic signal in a different active repeating FRB, FRB 20201124A. The authors use phase-folding and analyze data on a day-by-day basis, finding no significant periodicity on most days but identifying clear signals on two days. They measure periods of 1.706024(13) seconds (MJD 59310) and 1.707968(9) seconds (MJD 59347), and a global Monte Carlo analysis gives a 5.5σ significance. From the period change they infer a period derivative, corresponding magnetic field strength, and spin-down age, concluding the source is consistent with a young magnetar.
