Non-thermal radiation from a runaway massive star

TL;DR

This paper reports the detection of non-thermal synchrotron radio emission from a runaway massive star's bow shock, modeling its spectral energy distribution and predicting potential gamma-ray detection with future telescopes.

Contribution

It provides the first observational evidence of non-thermal emission from such a star and models its high-energy spectrum, suggesting detectability with upcoming gamma-ray observatories.

Findings

Detected non-thermal radio emission confirming particle acceleration

Modeled spectral energy distribution extending to gamma-rays

Predicted potential detection with future Cherenkov Telescope Array

Abstract

We present a study of the radio emission from a massive runaway star. The star forms a bow shock that is clearly observed in the infrared. We have performed VLA observations under the assumption that the reverse shock in the stellar wind might accelerate charged particles up to relativistic energies. Non-thermal radio emission of synchrotron origin has been detected, confirming the hypothesis. We have then modeled the system and we predict a spectral energy distribution that extends up to gamma-rays. Under some simplifying assumptions, we find that the intensity at high energies is too low to be detected by current instruments, but the future Cherenkov Telescope Array might detect the source.