IRAS observations of radio galaxies

Abstract

IRAS measurements at 25, 60, and 100 fim have been used to analyze the far-infrared properties of radio galaxies. Fifty-eight of the 131 objects surveyed were detected at the level of better than 300 mJy at 60 fim. The most powerful radio galaxies are strong emitters in the far infrared. They have luminosi-ties that are close to those of Markarian Seyfert galaxies, with 50% having 60 fim luminosities > 10 9 8 Lg,. Large infrared emission is shown to be correlated with the presence of strong emission lines in the optical spectra. The infrared colors of the strong radio galaxies are similar to those of Markarian Seyferts. Our results are shown to be consistent with recent results implying that the host galaxies of radio sources are not normal giant ellipticals and that galaxy-galaxy interactions may power luminous radio sources. Finally, some similarities between powerful radio galaxies and powerful infrared galaxies are noted and briefly discussed.