ONLINE-COLLOQUIUM: Dr. Natasha Hurley-Walker (Curtin University, Australia)

An ultra-long period radio transient

In the two decades, several puzzling radio transients have been detected using low-frequency radio telescopes, signalling intriguing high-energy events in our sky. The paucity of data on these objects has made it impossible to understand their nature. New wideband widefield telescopes are expanding the parameter space, improving our ability to detect and understand these events. We have detected a new type of low-frequency radio transient using a sky survey performed by the Murchison Widefield Array. The source's emission is bright, highly polarised, and periodic on a timescale of ~20 minutes. Its dynamic spectrum shows high-fluence narrow-timescale “spikes” which are unresolved by our data, with fluence on par with Fast Radio Bursts generated by the Galactic centre magnetar. I will highlight the object’s main observational features, including its window of appearance, dispersion measure, polarisation attributes, and changes in its pulse profile over time. Along with X-ray and optical observations, these features have allowed us to constrain its physical attributes such as location in the Galaxy, radio luminosity, and potential magnetic field strength, which I will detail in this talk. The source is potentially an “ultra-long period” (ULP) magnetar, which are candidate progenitors for Fast Radio Bursts. I will also postulate some alternative explanations and describe how we could narrow the possibilities with future observations. Finally, I will describe upcoming observing campaigns that will help us detect further examples, and perform rapid follow-up.

Talk in English language

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