First X-ray observations of Low-Power Compact Steep Spectrum Sources
  We report first X-ray Chandra observations of a sample of seven low
luminosity compact (LLC) sources. They belong to a class of young compact steep
spectrum (CSS) radio sources. Four of them have been detected, the other three
have upper limit estimations for X-ray flux, one CSS galaxy is associated with
an X-ray cluster. We have used the new observations together with the
observational data for known strong CSS and gigahertz-peaked spectrum (GPS)
objects and large scale FRIs and FRIIs to study the relation between
morphology, X-ray properties and excitation modes in radio-loud AGNs. We found
that: (1) The low power objects fit well to the already established X-ray -
radio luminosity correlation for AGNs and occupy the space among, weaker in the
X-rays, FRI objects. (2) The high excitation galaxies (HEG) and low excitation
galaxies (LEG) occupy distinct locus in the radio/X-ray luminosity plane,
notwithstanding their evolutionary stage. This is in agreement with the
postulated different origin of the X-ray emission in these two group of
objects. (3) We have tested the AGN evolution models by comparing the
radio/X-ray luminosity ratio with the size of the sources, and indirectly, with
their age. We conclude that the division for two different X-ray emission
modes, namely originate in the base of the relativistic jet (FRIs) or in the
accretion disk (FRIIs) is already present among the younger compact AGNs. (4)
Finally, we found that the CSS sources are less obscured than the more compact
GPSs in X-rays. However, the anti-correlation between X-ray column density and
radio size does not hold for the whole sample of GPS and CSS objects.
