The radio counterpart of the likely TeV binary HESS J0632+057

TL;DR

This study identifies and characterizes the radio counterpart of the TeV binary candidate HESS J0632+057, revealing variable radio emission consistent with gamma-ray binary systems, and suggesting it as a lower power analogue of known systems.

Contribution

First detection of radio emission from HESS J0632+057, establishing its variability and spectral properties, and proposing it as a new gamma-ray binary candidate.

Findings

Detected radio source at the star's position with spectral index ~0.6.

Observed flux variability on month timescales.

Radio properties align with known gamma-ray binaries.

Abstract

The few known gamma-ray binary systems are all associated with variable radio and X-ray emission. The TeV source HESS J0632+057, apparently associated with the Be star MWC148, is plausibly a new member of this class. Following the identification of a variable X-ray counterpart to the TeV source we conducted GMRT and VLA observations in June-September 2008 to search for the radio counterpart of this object. A point-like radio source at the position of the star is detected in both 1280 MHz GMRT and 5 GHz VLA observations, with an average spectral index, alpha, of ~0.6. In the VLA data there is significant flux variability on ~month timescales around the mean flux density of ~0.3 mJy. These radio properties (and the overall spectral energy distribution) are consistent with an interpretation of HESS J0632+057 as a lower power analogue of the established gamma-ray binary systems.