There has been a rapid increase in the known fast radio burst (FRB) population, yet the progenitor(s) of these events have remained an enigma. A small number of FRBs have displayed some level of quasi-periodicity in their burst profile, which can be used to constrain their plausible progenitors. However, these studies suffer from the lack of polarisation data which can greatly assist in constraining possible FRB progenitors and environments. Dial et al. report on the detection and characterisation of FRB 20230708A by ASKAP, a burst which displays a rich temporal and polarimetric morphology. They model the burst time series to test for the presence of periodicity, scattering and scintillation. They find a potential period of 7.267 ms within the burst, although with a low statistical significance. The majority of the properties of FRB 20230708A are broadly consistent with a (non-millisecond) magnetar model in which the quasi-periodic morphology results from microstructure in the beamed emission, although other explanations are not excluded.

The figure above shows the FRB profile and dynamic spectrum. Top Panel: Stokes I (total intensity) burst profile with full burst model shown in orange which consists of 21 Gaussian pulses convolved with a one-sided exponential. The black dashed lines underneath the burst profile illustrate the 7 segments the burst was separated into for fitting the full burst. The two largest peaks in the first bright sub-burst are labelled B1 and B2. Middle Panel: Residuals of burst fitting. Bottom Panel: Stokes I dynamic spectrum. The burst data has been further averaged to 40𝜇s time resolution 8 MHz frequency resolution for visual aid.