Disentangling the Nature of the Radio Emission in Wolf Rayet Stars

TL;DR

This study uses multi-frequency radio observations to analyze the emission mechanisms of Wolf Rayet stars, distinguishing thermal and non-thermal contributions, and identifying potential binary system effects.

Contribution

It provides the first detailed spectral analysis of a sample of Wolf Rayet stars, identifying thermal, non-thermal, and composite emission types, and discusses their emission origins.

Findings

Identified four thermal radio sources.

Detected three sources with composite spectra.

Confirmed non-thermal emission in one star.

Abstract

We present quasi-simultaneous, multi-frequency VLA observations at 4.8, 8.4, and 22.5 GHz, of a sample of 13 Wolf Rayet (WR) stars, aimed at disentangling the nature of their radio emission and the possible detection of a non-thermal behavior in close binary systems. We detected 12 stars from our sample, for which we derived spectral information and estimated their mass loss rates. From our data, we identified four thermal sources (WR 89, 113, 138, and 141), and three sources with a composite spectrum (similar contribution of thermal and non-thermal emission; WR 8, 98, and 156). On the other hand, from the comparison with previous observations, we confirm the non-thermal spectrum of one (WR 105), and also found evidence of a composite spectrum for WR 79a, 98a, 104, and 133. Finally, we discuss the possible scenarios to explain the nature of the emission for the observed objects.