Mid-Infrared Diagnostics of the Circumnuclear Environments of the
  Youngest Radio Galaxies
  We present a systematic analysis of the mid-infrared (MIR) properties of the
youngest radio galaxies, based on low-resolution data provided by the {\it
WISE} and {\it IRAS} satellites. We restrict our analysis to sources with
available X-ray data that constitute the earliest phase of radio galaxy
evolution, i.e. those classified as Gigahertz Peaked Spectrum (GPS) and/or
Compact Symmetric Objects (CSOs). In our sample of 29 objects, we find that the
host galaxies are predominantly red/yellow ellipticals, with some of them
displaying distorted morphology. We find a variety of MIR colors, and observe
that the sources in which the MIR emission is dominated by the ISM component
uniformly populate the region occupied by galaxies with a wide range of
pronounced ($\geq 0.5 M_{\odot}$\,yr$^{-1}$) star formation activity. We
compare the MIR color distribution in our sample to that in the general
population of local AGN, in the population of evolved FR\,II radio galaxies,
and also in the population of radio galaxies with recurrent jet activity. We
conclude that the triggering of radio jets in AGN does not differentiate
between elliptical hosts with substantially different fractions of young stars;
instead there is a relationship between the jet duty cycle and the ongoing star
formation. The distribution of the sub-sample of our sources with $z<0.4$ on
the low-resolution MIR vs. absorption-corrected X-ray luminosity plane is
consistent with the distribution of a sample of local AGN. Finally, we comment
on the star formation rates of the two $\gamma$-ray detected sources in our
sample, 1146+596 \& 1718--649.
