# Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: II. The Nature of the Radio Sources

## TL;DR

This study investigates the nature of weak, compact radio sources in early high-mass star-forming regions, providing evidence that many are ionized jets or pressure-confined HII regions, supporting jet-based models of early stellar ionization.

## Contribution

It offers new observational evidence that a significant fraction of early high-mass star radio sources are ionized jets, aligning with recent theoretical models and extending understanding of star formation processes.

## Key findings

- Approximately 30% of sources are ionized jets.
- Radio luminosity correlates strongly with bolometric luminosity.
- Supports jet-based models of early high-mass star ionization.

## Abstract

In this study we analyze 70 radio continuum sources associated with dust clumps and considered to be candidates for the earliest stages of high-mass star formation. The detection of these sources was reported by Rosero et al. (2016), who found most of them to show weak (${\scriptstyle <}$1 mJy) and compact (${\scriptstyle <}\,$0.6$^{\prime \prime}$) radio emission. Herein, we used the observed parameters of these sources to investigate the origin of the radio continuum emission. We found that at least $\sim 30\%$ of these radio detections are most likely ionized jets associated with high-mass protostars, but for the most compact sources we cannot discard the scenario that they represent pressure-confined HII regions. This result is highly relevant for recent theoretical models based on core accretion that predict the first stages of ionization from high-mass stars to be in the form of jets. Additionally, we found that properties such as the radio luminosity as a function of the bolometric luminosity of ionized jets from low and high-mass stars are extremely well-correlated. Our data improve upon previous studies by providing further evidence of a common origin for jets independently of luminosity.