Discovery of radio emission from the symbiotic X-ray binary system GX 1+4

TL;DR

This paper reports the first detection of radio emission from the symbiotic X-ray binary GX 1+4, suggesting possible jet activity or magnetosphere interactions, and challenges assumptions about magnetic fields suppressing jet formation.

Contribution

It presents the first radio detection of a symbiotic X-ray binary with a strongly magnetized neutron star, expanding understanding of radio emissions in such systems.

Findings

Detected 9 GHz radio flux density of 105.3 μJy from GX 1+4

Radio emission could be from shocks, jets, or outflows, not stellar wind

Strong magnetic fields may not prevent jet formation in such systems

Abstract

We report the discovery of radio emission from the accreting X-ray pulsar and symbiotic X-ray binary GX 1+4 with the Karl G. Jansky Very Large Array. This is the first radio detection of such a system, wherein a strongly magnetized neutron star accretes from the stellar wind of an M-type giant companion. We measure a $9$ GHz radio flux density of $105.3 \pm 7.3$ $\mu$Jy, but cannot place meaningful constraints on the spectral index due to a limited frequency range. We consider several emission mechanisms that could be responsible for the observed radio source. We conclude that the observed properties are consistent with shocks in the interaction of the accretion flow with the magnetosphere, a synchrotron-emitting jet, or a propeller-driven outflow. The stellar wind from the companion is unlikely to be the origin of the radio emission. If the detected radio emission originates from a jet, it would show that that strong magnetic fields ($\geq 10^{12}$ G) do not necessarily suppress jet formation.