2019A&A...623L...3S

Centimeter continuum observations of protostellar jets have revealed knots of shocked gas where the flux density decreases with frequency. This spectrum is characteristic of nonthermal synchrotron radiation and implies both magnetic fields and relativistic electrons in protostellar jets. Here, we report on one of the few detections of a nonthermal jet driven by a young massive star in the star-forming region G035.02+0.35. We made use of the NSF's Karl G. Jansky Very Large Array (VLA) to observe this region at C, Ku, and K bands with the A- and B-array configurations, and obtained sensitive radio continuum maps down to an rms of 10µJy/beam. These observations allow for a detailed spectral index analysis of the radio continuum emission in the region, which we interpret as a protostellar jet with a number of knots aligned with extended 4.5µm emission. Two knots clearly emit nonthermal radiation and are found at similar distances, of approximately 10000au, at each side of the central young star, from which they expand at velocities of several hundred km/s. We estimate both the mechanical force and the magnetic field associated with the radio jet, and infer a lower limit of 0.4x10^–4M_☉/yr.km/s and values in the range 0.7-1.3mG.