The Origin of the Infrared Emission in Radio Galaxies. I. New Mid‐ to Far‐Infrared and Radio Observations of the 2 Jy Sample

Abstract

As part of a large study to investigate the nature of the longer wavelength continuum emission of radio-loud AGNs, we present new mid-to far-infrared (MFIR) and high-frequency radio observations for a complete sample of 2 Jy powerful southern radio galaxies at intermediate redshifts (0:05 < z < 0:7). Utilizing the sensitivity of the Spitzer Space Telescope, we have made deep MIPS observations at wavelengths of 24, 70, and 160 m, detecting 100% of our sample at 24 m and 90% at 70 m. This high detection rate at MFIR wavelengths is unparalleled in samples of intermediate-redshift radio galaxies. Complementing these results, we also present new high-frequency observations (15Y24 GHz) from the Australia Telescope Compact Array and the Very Large Array, which are used to investigate the potential contamination of the MFIR continuum by nonthermal synchrotron emission. With the latter observations we detect compact cores in 59% of our complete sample and deduce that nonthermal contamination of the MFIR continuum is significant in a maximum of 30% of our total sample. MFIR fluxes, radio fluxes, and spectral energy distributions for the complete sample are presented here, while in a second paper we will analyze these data and discuss the implications for our understanding of the heating mechanism for the warm/cool dust, star formation in the host galaxies, and the unified schemes for powerful radio sources.