A Galactic survey of radio jets from massive protostars

In conjunction with a previous southern-hemisphere work, we present the largest radio survey of jets from massive protostars to date with high-resolution (∼0.04 arcsec) Jansky Very Large Array observations towards two subsamples of massive star-forming regions of different evolutionary statuses: 48 infrared-bright, massive, young, stellar objects (MYSOs) and 8 infrared dark clouds (IRDCs) containing 16 luminous (⁠Lbol>103L⊙⁠) cores. For 94 per cent of the MYSO sample, we detect thermal radio (α ≥ −0.1 whereby Sν ∝ να) sources coincident with the protostar, of which 84 per cent (13 jets and 25 candidates) are jet like. Radio luminosity is found to scale with Lbol similarly to the low-mass case supporting a common mechanism for jet production across all masses. Associated radio lobes tracing shocks are seen towards 52 per cent of jet-like objects and are preferentially detected towards jets of higher radio and bolometric luminosities, resulting from our sensitivity limitations. We find jet mass-loss rate scales with bolometric luminosity as m˙jet∝Lbol0.9±0.2⁠, thereby discarding radiative, line-driving mechanisms as the dominant jet-launching process. Calculated momenta show that the majority of jets are mechanically capable of driving the massive, molecular outflow phenomena since pjet > poutflow. Finally, from their physical extent we show that the radio emission cannot originate from small, optically thick H II regions. Towards the IRDC cores, we observe increasing incidence rates/radio fluxes with age using the proxy of increasing luminosity-to-mass (L/M) and decreasing infrared flux ratios (S70μm/S24μm)⁠. Cores with (L/M)<40L⊙M⊙−1 are not detected above (⁠5.8GHz⁠) radio luminosities of ∼1mJykpc2⁠.