Discovery of a 36-minute long-period transient ASKAP J142431.2-612611

TL;DR

A new long-period radio transient with a 36-minute cycle was discovered, showing unique polarisation behavior and intermittent activity, expanding understanding of such transient sources.

Contribution

This paper reports the first detection of a 36-minute long-period radio transient with unique polarisation characteristics and intermittent activity, adding to the known class of long-period transients.

Findings

Detected a 36-minute period radio transient ASKAP J142431.2-612611.

Observed stable, highly polarised pulse profile evolving from elliptical to linear polarisation.

Source exhibited intermittent activity, switching off after eight days.

Abstract

We report the discovery of a new long-period radio transient, ASKAP J142431.2-612611, with a 36 minute period, identified in the Australian SKA Pathfinder Evolutionary Map of the Universe survey. We detected pulsed emission from ASKAP J142431.2-612611 over a period of eight days during follow-up observations with the Australia Telescope Compact Array, after which the source appears to have switched off. No optical or near-infrared counterpart is detected in archival surveys or in targeted Gemini South FLAMINGOS-2 observations. During its active state, the source exhibits a stable pulse profile with fractional polarisation consistent with 100%, evolving from elliptically to linearly polarised and tracing a well-defined great-circle trajectory on the Poincar\'e sphere. We show that this behaviour is consistent with fully linearly polarised intrinsic emission modified by propagation through a linearly polarised birefringent medium. This discovery expands the known population of long-period transients and highlights the intermittent nature of their activity. We discuss the implications for proposed models of long-period transients and outline future observations needed to constrain the origin of their intermittency and polarisation properties.