Determine the binary nature of GPM J1832−09

Determine whether GPM J1832−09 is a binary system, specifically an ultra-compact asynchronous polar consisting of a magnetic white dwarf and a companion star.

Background

The paper interprets the evolving pulse morphology, phase-resolved rotation-measure variation, polarisation properties, and periodic X-ray emission of GPM J1832−09 using a nearly synchronised close-binary model. In this interpretation, the source would be an ultra-compact asynchronous polar whose white-dwarf spin and orbital periods differ slightly.

Although the proposed model accounts for much of the observed phenomenology and generates testable predictions, the available observations do not establish the presence of a companion or conclusively distinguish the binary interpretation from magnetar or other alternatives. Further observations, including monitoring for the predicted radio re-brightening and searches for an optical counterpart, are relevant to resolving this question.

References

We show that an ultra-compact asynchronous polar explains much of the phenomenology of {1832 long}, in particular the evolution of the pulse morphology, rotation measure variation, and periodic X-ray emission, although we cannot conclusively prove a binary nature.

— Evidence for the binary nature of the long-period radio transient ASKAP/DART J1832-0911  (2609.11068 - Horváth et al., 10 Sep 2026) in Abstract (p. 1)