Origin of the radio emission from A0538−66

Determine the physical origin of the radio emission from the Be/neutron-star binary A0538−66 by distinguishing among discrete ejecta, an outflow powered by a propeller mechanism, and a shock between a pulsar wind and the circumstellar material.

Background

A0538−66 was recently detected at radio wavelengths by ASKAP and subsequently monitored with MeerKAT. The source is unusually radio luminous for a neutron-star X-ray binary, and its radio emission appears to be orbitally modulated, peaking shortly after the optical maximum near periastron.

The physical mechanism producing this radio emission has not been established. The paper identifies three viable interpretations—discrete ejecta, a propeller-powered outflow, or a shock formed by interaction between a pulsar wind and circumstellar material—making the origin of the radio emission an unresolved problem.