Long-period radio transients

The long-period radio transients are an emerging class of objects characterised by polarised periodic broadband pulses lasting several minutes with periodicities on timescales of tens of minutes. One of the most recent to be published, GPMJ1839-10, has a period derivative that places it below the “death lines” for radio emission from neutron stars (Hurley-Walker et al. 2023) and white dwarfs (Rea et al. 2023). Theoretical frameworks for the radio emission from these unusual objects include magnetars and white dwarf pulsars, although there are significant challenges in reconciling the data with either model.

MeerKAT has been critical in characterising the radio emission from these sources, offering spectral-polarimetric data of unparalleled sensitivity on critical timescales (seconds to tens of minutes) that enables the production of high-quality dynamic spectra of the pulses. This is leading to advances in the modelling of the magnetospheres that must be causing the emission. The high-time-resolution backends such as PTUSE are also essential for understanding the short-timescale behaviour, e.g. the discovery of ms-duration orthogonal polarisation modes in GPMJ1839-10, and will be essential for determining whether such objects are progenitors for Fast Radio Bursts, as predicted by some theories (Wadiasingh et al, 2020; Beniamini et al. 2020).

In this talk I will give an update on our latest observations of these unusual objects, including new MeerKAT data and how it has enabled critical follow up at other wavelengths. I will also discuss how MeerKAT can be used not just for follow-up, but also for discovery, and what that would tell us about the population in our Galaxy.