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

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 mu m, detecting 100% of our sample at 24 mu m and 90% at 70 mu 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 (15-24 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.

[1]  G. Neugebauer,et al.  Quasars Measured by the Infrared Astronomical Satellite , 1986 .

[2]  G. Neugebauer,et al.  IRAS observations of radio galaxies , 1988 .

[3]  Peter D. Barthel,et al.  Is every quasar beamed , 1989 .

[4]  G. Knapp,et al.  Infrared properties of nearby radio galaxies , 1990 .

[5]  M. Postman,et al.  The infrared properties of quasars and radio galaxies - Testing the unification schemes , 1992 .

[6]  C. Impey,et al.  Energy distributions of radio galaxies , 1993 .

[7]  R. Morganti,et al.  Optical spectroscopy of a complete sample of southern 2-Jy radio sources , 1993 .

[8]  R. Morganti,et al.  The radio structures of southern 2-Jy radio sources , 1993 .

[9]  R. Morganti,et al.  New identifications and redshifts for southern 2-Jy radio sources , 1994 .

[10]  T. Heckman,et al.  Obscuration, Orientation, and the Infrared Properties of Radio-loud Active Galaxies , 1994 .

[11]  Michael Rowan-Robinson,et al.  A new model for the infrared emission of quasars , 1995 .

[12]  J. Reynolds,et al.  A study of cores in a complete sample of radio sources , 1997 .

[13]  Steve Rawlings,et al.  High-redshift radio galaxies and quasars at submillimetre wavelengths: assessing their evolutionary status , 1997, astro-ph/9705094.

[14]  R. Morganti,et al.  The nature of the optical–radio correlations for powerful radio galaxies , 1998, astro-ph/9807238.

[15]  D. Lemke,et al.  On the Far-Infrared Emission of Quasars , 1998 .

[16]  R. Morganti,et al.  The radio structures of southern 2-Jy radio sources: New ATCA and VLA radio images , 1999, astro-ph/9910150.

[17]  U. Klaas,et al.  Dust emission from 3C radio galaxies and quasars: New ISO observations favour the unified scheme , 2001, astro-ph/0102333.

[18]  J. Dunlop,et al.  A submillimetre survey of the star formation history of radio galaxies , 2000, astro-ph/0002083.

[19]  Dayton L. Jones,et al.  A sample of southern Compact Steep Spectrum radio sources: the VLBI observations , 2002, astro-ph/0207495.

[20]  R. Morganti,et al.  The ultraviolet excess in nearby powerful radio galaxies: evidence for a young stellar component , 2002 .

[21]  R. Morganti,et al.  The origin of the UV excess in powerful radio galaxies: spectroscopy and polarimetry of a complete sample of intermediate‐redshift radio galaxies , 2002, astro-ph/0201391.

[22]  India.,et al.  3C 459: a highly asymmetric radio galaxy with a starburst , 2003, astro-ph/0305176.

[23]  A multiband study of Hercules A - II. Multifrequency Very Large Array imaging , 2003, astro-ph/0305600.

[24]  O. Krause,et al.  The ISOPHOT-MAMBO survey of 3CR radio sources: Further evidence for the unified schemes , , 2004, astro-ph/0406111.

[25]  Emission lines and optical continuum in low - luminosity radio galaxies , 2003, astro-ph/0310256.

[26]  Paul S. Smith,et al.  The Multiband Imaging Photometer for Spitzer (MIPS) , 2004 .

[27]  G. Neugebauer,et al.  Far-Infrared Observations of Radio Quasars and FR II Radio Galaxies , 2005, astro-ph/0504622.

[28]  G. Zotti,et al.  High-frequency radio observations of the Kühr sample and the epoch-dependent luminosity function of flat-spectrum quasars , 2005 .

[29]  Granada,et al.  The co-evolution of the obscured quasar PKS 1549-79 and its host galaxy : evidence for a high accretion rate and warm outflow , 2006, astro-ph/0606304.

[30]  Alan Bridger,et al.  Advanced software and control for astronomy : 24-26 May 2006, Orlando, Florida, USA , 2006 .

[31]  C. I. O. Technology.,et al.  Spitzer Observations of 3C Quasars and Radio Galaxies: Mid-Infrared Properties of Powerful Radio Sources , 2006, astro-ph/0612702.

[32]  Wm. A. Wheaton,et al.  Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. II. 70 μm Imaging , 2007, 0704.2196.

[33]  D. Padgett,et al.  Absolute Calibration and Characterization of the Multiband Imaging Photometer for Spitzer. I. The Stellar Calibrator Sample and the 24 μm Calibration , 2007, 0704.2195.

[34]  The Heating Mechanism for the Warm/Cool Dust in Powerful, Radio-loud Active Galactic Nuclei , 2007, astro-ph/0703790.

[35]  R. Morganti,et al.  The properties of the young stellar populations in powerful radio galaxies at low and intermediate redshifts , 2007, 0708.2605.

[36]  R. Faix,et al.  Red Book: 2006 Report of the Committee on Infectious Diseases, 27th Edition Edited by Larry K. Pickering, Carol F. Baker, Sarah S. Long, and Julia A. McMillan Elk Grove Village, IL: American Academy of Pediatrics, 2006. 992 pp. $124.95 (cloth) , 2007 .

[37]  Italy.,et al.  On the nature of optical nuclei in FR I radio-galaxies from ACS/HST imaging polarimetry , 2007, 0706.1944.

[38]  R. Davies,et al.  Astronomical Society of the Pacific Conference Series , 2010 .