In recent years, a class of long-period radio transients (LPTs) has been discovered, exhibiting emission on timescales thousands of times longer than radio pulsars. Various models have been proposed involving either a strong magnetic field neutron star, isolated white dwarf pulsar, or a white dwarf binary system with a low-mass companion. While several models for LPTs also predict X-ray emission, no LPTs had previously been detected in X-rays despite extensive searches. Wang et al. report the discovery of an extremely bright LPT, ASKAP J1832-0911, which has coincident radio and X-ray emission, both modulated with a 44.2-minute period, as illustrated above. The LPT was identified as a compact circularly polarised transient radio source as part of the ASKAP Variables and Slow Transients survey. The team consider a magnetar at least 500,000 years old magnetar with a 1013 gauss crustal field, or an extremely magnetised white dwarf in a binary system with a dwarf companion, to be plausible explanations for ASKAP J1832-0911, although both explanations pose significant challenges to formation and emission theories. This work is described in an article in The Conversation. (Image credit: Ziteng Wang)
