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arXiv · 2601.22741

Detection of an Extremely Luminous Radio Counterpart to the Be/X-ray Binary A0538-66

Justine Crook-Mansour·Rob Fender·Alex Andersson·Hao Qiu·Andrew K. Hughes·Jakob van den Eijnden·Fraser J. Cowie·Sara Motta·Itumeleng Monageng·Lorenzo Ducci·Sandro Mereghetti·Andries Mathiba·Dougal Dobie·Tara Murphy·David L. Kaplan·Francesco Carotenuto·Phil Charles
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Abstract

We present the discovery of radio emission from the Be/X-ray binary A0538-66 with the Australian Square Kilometre Array Pathfinder (ASKAP), and results from a subsequent weekly monitoring campaign with the MeerKAT radio telescope. A0538-66, located in the Large Magellanic Cloud, hosts a neutron star with a short spin period ($P \approx 69$ ms) in a highly eccentric $\approx16.6$-day orbit. Its rare episodes of super-Eddington accretion, rapid optical and X-ray flares, and other peculiar properties make it an interesting system among high-mass X-ray binaries. Our MeerKAT data reveal that it is also one of the most radio-luminous neutron star X-ray binaries observed to date, reaching $\approx 3 \times 10^{22}~\text{erg}~\text{s}^{-1} \text{Hz}^{-1}$, with radio emission that appears to be orbitally modulated. We consider several possible mechanisms for the radio emission, and place A0538-66 in context by comparing it to similar systems.

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Justine Crook-Mansour, Rob Fender, Alex Andersson, Hao Qiu, Andrew K. Hughes, Jakob van den Eijnden, Fraser J. Cowie, Sara Motta, Itumeleng Monageng, Lorenzo Ducci, Sandro Mereghetti, Andries Mathiba, Dougal Dobie, Tara Murphy, David L. Kaplan, Francesco Carotenuto, Phil Charles. 2026-01-30. Detection of an Extremely Luminous Radio Counterpart to the Be/X-ray Binary A0538-66. https://arxiv.org/abs/2601.22741

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