X-Ray data

PKS1814-63

Optical spectrum taken with ESO telescopes.

Tadhunter et al. (1993)

PKS1814-63

Spitzer IRS spectra

Dicken et al. (in preperation)

0.063

18 19 34.96

-63 45 48.1

NLRG

CSS

-

N

E

Notes

    This galaxy is the subject of a detailed study by the 2Jy collaboration (Morganti et al 2011). PKS 1814-637, a rare case of powerful radio source (P_5GHz = 4.1 × 10^25 W Hz−1) 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 to the line of sight. This is the first radio galaxy found to reside in a disk dominated galaxy with radio luminosity equivalent to powerful FRII objects. At radio wavelengths, PKS 1814-637 is about 480 pc in diameter and it is classified as a compact steep spectrum (CSS) 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 which is likely to be related to the disk morphology of the host galaxy. We argue that 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, PKS 1814-637 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 PKS 1814-637 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 unlikely that jet-cloud interactions alone can account for the unusually powerful radio emission compared to Seyfert galaxies, and it is probable that the jet in PKS 1814-637 is also intrinsically more powerful than in typical Seyfert galaxies, perhaps due to a higher bulge and black hole mass. 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, because of the enhanced probability at earlier epochs of triggering radio sources in moderately massive bulges that are also gas-rich (Morganti et al. 2011).

    Starburst activity has been identified in MFIR observations of this object, based on the detection of a FIR excess and low equivalent width PAH features (Dicken et al. 2009, 2011). The Gemini GMOS-S shows a straight dust lane of diameter ∼20 kpc. This, along with highly elongated, discy isophotes, is consistent with the morphological classification of this system as an S0 or Sa galaxy viewed close to edge-on. However, the outer disc of the galaxy is clearly highly distorted. Similar features (a faint extended disc feature and a possible dust lane) are observed in the model-subtracted K-band image analysed by Inskip et al. (2010). Long-slit spectra of this galaxy confirm that emission-line contamination is not a serious issue for the outer distorted features.

    Further details of the ionization and kinematics of the emission line gas in this source are discussed in Holt et al. (2008, MNRAS, 387, 639) and Holt et al. (2009, MNRAS, 400, 589) respectively.

Gemini/GMOS-S: median filtered image

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