PKS 1814-637: a powerful radio-loud AGN in a disk galaxy
  We present a detailed study of PKS1814-637, a rare case of powerful radio
source (P_5 GHz = 4.1 x 10^25 W/Hz) hosted by a disk galaxy. Optical images
have been used to model the host galaxy morphology confirming it to be
dominated by a strong (and warped) disk component that is observed close to
edge-on. At radio wavelengths, PKS1814-637 is about 480 pc in diameter and it
is classified as a compact steep spectrum source; such sources are usually
considered to be radio sources observed in the early stages of their evolution.
However, the optical and mid-IR spectroscopic properties of PKS1814-637 show
more in common with Seyfert galaxies than they do with radio galaxies, with the
detection of H_2, and PAH emission features, along with HI and silicate
absorption features, providing evidence for a rich ISM, likely related to the
disk morphology of the host galaxy. The interaction between the radio plasma
and the rich ISM in this and similar objects may have boosted their radio
emission, allowing them to more easily enter flux limited samples of radio
sources. In this case, PKS1814-637 represents a type of "imposter": an
intrinsically low power object that is selected in a radio flux limited sample
because of the unusually efficient conversion of jet power into radio emission.
This would make PKS1814-637 an extreme example of the effects of jet-cloud
interactions in galaxies containing a rich ISM, and perhaps a missing link
between radio galaxies and radio-loud Seyfert galaxies. However, it is probable
that the jet in PKS1814-637 is also intrinsically more powerful than in typical
Seyfert galaxies. The estimated BH mass is indeed higher than the majority of
Seyfert galaxies in the local Universe. We speculate that sources similar to
PKS1814-637 are likely to be more common at high redshifts.
