The multi-frequency parsec-scale structure of PKS 2254-367 (IC 1459): a
  luminosity-dependent break in morphology for the precursors of radio
  galaxies?
  We present the first multi-frequency VLBI images of PKS 2254-367, a
Giga-hertz Peaked Spectrum (GPS) radio source hosted by the nearby galaxy IC
1459 (D=20.5 Mpc). PKS 2254-367 and the radio source in NGC 1052 (PKS 0238-084;
D=17.2 Mpc) are the two closest GPS radio sources to us, far closer than the
next closest example, PKS 1718-649 (D=59 Mpc). As such, IC 1459 and NGC 1052
offer opportunities to study the details of the pc-scale radio sources as well
as the environments that the radio sources inhabit, across the electromagnetic
spectrum. Given that some models for the origin and evolution of GPS radio
sources require a strong connection between the radio source morphology and the
gaseous nuclear environment, such opportunities for detailed study are
important. Our VLBI images of PKS 2254-367 show that the previously identified
similarities between IC 1459 and NGC 1052 continue onto the pc-scale. Both
compact radio sources appear to have symmetric jets of approximately the same
luminosity, much lower than typically noted in compact double GPS sources.
Similarities between PKS 2254-367 and NGC 1052, and differences with respect to
other GPS galaxies, lead us to speculate that a sub-class of GPS radio sources,
with low luminosity and with jet-dominated morphologies, exists and would be
largely absent from radio source surveys with ~1 Jy flux density cutoffs. We
suggest that this possible low-luminosity, jet-dominated population of GPS
sources could be an analog of the FR-I radio galaxies, with the higher
luminosity lobe-dominated GPS sources being the analog of the FR-II radio
galaxies.
