Sample Overview
The original 2Jy sample (Wall and Peacock 1985) includes all the radio sources with flux density above 2Jy at 2.7GHz . We have studied a sub-sample of this that encompasses the southern part (delta<+10 degrees) of this catalogue to study in detail the relationship between the radio, optical and X-ray properties of a complete sample. This sample consists of 88 objects: 68 galaxies, 18 quasars and 2 BL Lac objects and the optical and radio data is presented in Tadhunter et al. (1993) and Morganti et al. (1993).
For this sample, the following database is available:
1) radio data: data from the VLA and the Australia Telescope Compact Array (ATCA) have been obtained at 5 GHz (resolution ~3 arcsec, see Morganti et al. 1993 and 1999 for details). These data, together with some collected from literature, have allowed a morphological classification of the sources according to Fanaroff & Riley (1974). An estimate of the core flux densities was obtained from PTI observations (Morganti et al. 1997). This is very important because it allows us to derive the parameter R (ratio of the core to the extended radio flux density) that is believed to be an important indicator of orientation. VLBI observations have been done for a number of objects included all the Compact Steep Spectrum (CSS) sources (Venturi et al. 1996, Tzioumis et al. 1996).
2) optical (spectroscopic) data: all the objects in the sample have a measurement (either a detection or an upper limit) for the [OIII]5007 emission line (Tadhunter et al. 1993 and 1998). The [OII]3727 was measured in 47 objects, and a measurement of the Hbeta is available for 40 objects. measurements of the flux and colour of the optical continuum have also been obtained. We also have broad-band polarimetry done for the radio galaxies with redshift between 0.15 and 0.7 (Tadhunter et al. 1997).
3) X-ray data: ROSAT data in the 0.1--2.4 keV energy band from the survey and from (public) pointed observations have been retrieved in order to determine the soft X-ray luminosities (Siebert et al. 1996). Using a maximum- likelihood source-detection algorithm we could detect 50 out of the 88 sources in the sample and a reliable upper limit could be set for the remaining 38.Observations were also done on some objects using the italian-dutch X-ray satellite SAX.
Steep spectrum sub-sample
With a sub-sample a sample that is complete in terms of optical emission line information and that is unbiased with respect to orientation we have complete observations with Spitzer (MIPS, IRS), high frequency radio core observations with ATCA and the VLA (15-24 GHZ) as well as a large proportion of this observed by Chandra
This sample unique sample comprises a complete subsample of all 46 steep-spectrum powerful radio galaxies and quasars with redshifts and flux densities Jy from the sample of Tadhunter et al. (1993). We use a steep spectrum selection, which excludes 16 objects within the redshift range 0.05<z<0.7. We also include PKS 0347+05, which has since been proved to fulfill the same selection criteria (di Serego-Alighieri et al. 1994). The lower redshift limit is set to ensure that these galaxies are genuinely powerful sources, and the steep-spectrum selection for the quasars rules out objects dominated by emission from the beamed relativistic jet and core components. Overall, the full sample of 46 objects includes a mixture of broad-line radio galaxies/radio-loud quasars (BLRGs/quasars; 35%), narrow-line radio galaxies (NLRGs; 43%), and weak-line radio galaxies (WLRGs; 22%). In terms of radio morphology classification, our complete sample includes 72% FR II sources, 13% FR I sources, and 15% compact steep-spectrum (CSS)/gigahertz peaked-spectrum (GPS) objects.
For comparison purposes we also observed or collected data from the Spitzer and IRAS archives for the flat-spectrum, core-dominated objects 3C 273, PKS 0521–36, and PKS 1549–79. Note that PKS 1549–79 is a particularly interesting source, because it a rare example of a powerful, flat-spectrum radio source that is classified as a galaxy at optical wavelengths; the nature of this object is discussed in detail in Holt et al. (2006). However, these objects are not part of what we refer to as our complete sample. Our complete sample of 46 objects comprises the 49 objects with Spitzer or IRAS observations presented below, minus the 3 comparison flat-spectrum objects.