Mon. Not. R. Astron. Soc., 448, 252-257 (2015/March-3)
The multifrequency parsec-scale structure of PKS 2254-367 (IC 1459): a luminosity-dependent break in morphology for the precursors of radio galaxies?
TINGAY S.J. and EDWARDS P.G.
Abstract (from CDS):
We present the first multifrequency very long baseline interferometry (VLBI) images of PKS 2254-367, a gigahertz-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 parsec-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 on to the parsec-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 cut-offs. We suggest that this possible low-luminosity, jet-dominated population of GPS sources could be an analogue of the Fanaroff-Riley type I (FR I) radio galaxies, with the higher luminosity lobe-dominated GPS sources being the analogue of the FR II radio galaxies.
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
techniques: high angular resolution - galaxies: active - galaxies: individual: PKS 2254-367 (IC 1459)
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