  Young Stellar Objects (YSOs) and in particular protostars are known to show a
variety of high-energy processes. Observations in the X-ray and centimetric
radio wavelength ranges are thought to constrain some of these processes, e.g.,
coronal-type magnetic activity. There is a well-known empirical correlation of
radio and X-ray luminosities in active stars, the so-called Guedel-Benz
relation. Previous evidence whether YSOs are compatible with this relation
remains inconclusive for the earliest evolutionary stages. The main difficulty
is that due to the extreme variability of these sources, simultaneous
observations are essential. Until now, only few YSOs and only a handful of
protostars have been observed simultaneously in the X-ray and radio range. To
expand the sample, we have obtained such observations of two young clusters
rich in protostars, NGC 1333 and IC 348. While the absolute sensitivity is
lower for these regions than for more nearby clusters like CrA, we find that
even in deep continuum observations carried out with the NRAO Very Large Array,
the radio detection fraction for protostars in these clusters is much lower
than the X-ray detection fraction. Very few YSOs are detected in both bands,
and we find the radio and X-ray populations among YSOs to be largely distinct.
We combine these new results with previous simultaneous Chandra and VLA
observations of star-forming regions and find that YSOs with detections in both
bands appear to be offset toward higher radio luminosities for given X-ray
luminosities when compared to the Guedel-Benz relation, although even in this
sensitive dataset most sources are too weak for the radio detections to provide
information on the emission processes. The considerably improved sensitivity of
the Expanded Very Large Array will provide a better census of the YSO radio
population as well as better constraints on the emission mechanisms.
