The ISOPHOT-MAMBO survey of 3CR radio sources: Further evidence for the unified schemes ,

We present the complete set of ISOPHOT observations of 3CR radio galaxies and quasars, which are contained in the ISO Data Archive, providing 75 mid- and far-infrared spectral energy distributions (SEDs) between 5 and 200  μ m. For 28 sources they are supplemented with MAMBO 1.2 mm observations and for 15 sources with new submillimetre data from the SCUBA archive. The sample includes flat and steep spectrum quasars, broad and narrow line radio galaxies, as well as Fanaroff-Riley FR 1 and FR 2 types. The SED shapes exhibit a diversity in the infrared (IR), ranging from a smooth dominating synchrotron component in flat spectrum sources to a thermal dust bump around 60-100  μ m in steep spectrum sources. The detection rate of a thermal bump in more than 50% of the cases suggests that dust emission may be a general phenomenon in these sources. We check the orientation-dependent unified scheme, in which the powerful FR 2 narrow line galaxies are quasars viewed at high inclination, so that their nuclei are hidden behind a dust torus intercepting the optical-ultraviolet AGN radiation and reemitting it in the infrared. We find that (1) both the quasars and the galaxies show a high mid- to far-infrared luminosity ratio typical for powerful AGNs and (2) – when matched in 178 MHz luminosity – both show the same ratio of isotropic far-infrared to isotropic 178 MHz lobe power. Therefore, from our large sample investigated here we find strong evidence for the orientation-dependent unification of the powerful FR 2 galaxies with the quasars. The distribution of the dust-to-lobe luminosity ratio shows a dispersion which we suggest to be most likely due to the additional influence of evolution and environment superposed on the orientation-dependent unification. We discuss our data also in the frame of the receding torus model. At the high 178 MHz luminosities of our sources above 10$^{\rm 26.5}$ W/Hz we do not find any support for this model in its original formulation and therefore we propose a refinement: The scale height of the torus might not be independent of luminosity, rather it may increase at high luminosities due to the impact of supernovae from starbursts accompanying the AGN phenomena.

[1]  R. Siebenmorgen,et al.  ISOCAM survey and dust models of 3CR radio galaxies and quasars , 2004 .

[2]  R. Siebenmorgen,et al.  Hot Dust in Radio-loud Active Galactic Nuclei , 2003, astro-ph/0311024.

[3]  P. J. Richards,et al.  The ISO Handbook, Volume IV - PHT - The Imaging Photo-Polarimeter , 2003 .

[4]  C. Dullemond,et al.  New radiative transfer models for obscuring tori in active galaxies , 2003, astro-ph/0303496.

[5]  Edward J. Wollack,et al.  First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results , 2003, astro-ph/0302207.

[6]  C. Simpson.  Quasars are more luminous than radio galaxies—so what? , 2003, astro-ph/0301098.

[7]  Belinda J. Wilkes,et al.  The ISO view of Palomar-Green quasars , 2003 .

[8]  K. Leech,et al.  The ISO handbook , 2003 .

[9]  C. Norman,et al.  Obscuring Material around Seyfert Nuclei with Starbursts , 2002, astro-ph/0201035.

[10]  J. Dunlop,et al.  A submillimetre difference between radio galaxies and radio quasars: evidence for quasar-heated dust and synchronized submillimetre and radio source activity , 2001, astro-ph/0111559.

[11]  Padova,et al.  Far-infrared/millimetre emission in 3C sources - Dust in radio galaxies and quasars , 2002 .

[12]  D. Lemke,et al.  Infrared to millimetre photometry of ultra-luminous ir galaxies: new evidence favouring a 3-stage dust model , 2001, astro-ph/0110213.

[13]  I. Coulson,et al.  The PAH 7.7 $\mu$m/850 $\mu$m ratio as new diagnostics for high extinction in ULIRGs -increasing evidence for a hidden quasar in Arp 220 , 2001 .

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

[15]  F. Bertoldi,et al.  Millimeter observations of radio-loud active galaxies , 2001, astro-ph/0101137.

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

[17]  U. Oxford,et al.  1–5 μm imaging of 3CRR galaxies: the K–z relation and the geometry of the torus , 2000, astro-ph/0007475.

[18]  K. Blundell,et al.  The Quasar Fraction in Low-Frequency Selected Complete Samples and Implications for Unified Schemes , 2000, astro-ph/0003461.

[19]  H. Tran,et al.  Polarimetry and Unification of Low-Redshift Radio Galaxies , 1999, astro-ph/9909215.

[20]  K. Blundell,et al.  The inevitable youthfulness of known high-redshift radio galaxies , 1999, Nature.

[21]  R. Laureijs,et al.  Isophot - photometric calibration of point sources , 1999, astro-ph/0111383.

[22]  E. I. Robson,et al.  Millimetre and submillimetre continuum observations of the core and hotspots of Cygnus A , 1998, astro-ph/9810382.

[23]  A. Cimatti,et al.  DUST IN 3C 324 , 1998, astro-ph/9809284.

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

[25]  E. I. Robson,et al.  Variability of the Centimeter-Submillimeter Spectrum and Polarization of 3C 273 during Outburst , 1998 .

[26]  C. Kaiser,et al.  Evolutionary tracks of FRII sources through the P-D diagram , 1997, astro-ph/9710104.

[27]  P. Barthel,et al.  Anomalous radio-loudness of Cygnus A and other powerful radio galaxies , 1996 .

[28]  A. Singal.  DIFFERENTIAL NUMBER COUNTS OF RADIO GALAXIES AND QUASARS : EVIDENCE AGAINST THE UNIFIED SCHEME , 1996 .

[29]  D. Depoy,et al.  Observations of Paschen alpha in a Complete Sample of Radio Galaxies , 1996 .

[30]  P. Padovani,et al.  UNIFIED SCHEMES FOR RADIO-LOUD ACTIVE GALACTIC NUCLEI , 1995, astro-ph/9506063.

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

[32]  Julian H. Krolik,et al.  Infrared Spectra of Obscuring Dust Tori around Active Galactic Nuclei. II. Comparison with Observations , 1993 .

[33]  David H. Hughes,et al.  Thermal dust emission from quasars – I. Submillimetre spectral indices of radio-quiet quasars , 1993 .

[34]  H. Netzer,et al.  Dust in the Narrow-Line Region of Active Galactic Nuclei , 1993 .

[35]  Julian H. Krolik,et al.  Infrared spectra of obscuring dust tori around active galactic nuclei. I - Calculational method and basic trends , 1992 .

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

[37]  A. Lawrence.  The relative frequency of broad-lined and narrow-lined active galactic nuclei: implications for unified schemes , 1991 .

[38]  D. J. Saikia,et al.  3C380: a powerful radio source seen end-on? , 1991 .

[39]  R. Antonucci,et al.  Narrow-line radio galaxies as quasars in the sky plane , 1990 .

[40]  Maarten Schmidt,et al.  VLA observations of objects in the Palomar Bright Quasar Survey , 1989 .

[41]  L. Miller,et al.  Spectrophotometry of FRII radiogalaxies in an unbiased, low-redshift sample , 1989 .

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

[43]  P. Barthel,et al.  Evolution of radio structure in quasars: a new probe of protogalaxies? , 1988, Nature.

[44]  Maarten Schmidt,et al.  Continuum energy distributions of quasars in the Palomar-Green Survey , 1987 .

[45]  S. Djorgovski,et al.  ERRATUM - A THIRD UPDATE OF THE STATUS OF THE 3CR SOURCES - FURTHER NEW REDSHIFTS AND NEW IDENTIFICATIONS OF DISTANT GALAXIES , 1985 .

[46]  J. Miller,et al.  Spectropolarimetry and the nature of NGC 1068 , 1985 .

[47]  M. Longair,et al.  Non-stellar radiation in radio galaxies at 3.5 microns , 1985 .

[48]  M. Longair,et al.  Stellar populations in distant radio galaxies , 1984 .

[49]  E. Young,et al.  A 25 micron component in 3C 390.3 , 1984 .

[50]  R. Antonucci.  Optical spectropolarimetry of radio galaxies. , 1984 .

[51]  M. Longair,et al.  Bright radio sources at 178 MHz: flux densities, optical identifications and the cosmological evolution of powerful radio galaxies , 1983 .

[52]  M. Orr,et al.  Relativistic beaming and quasar statistics , 1982 .

[53]  M. Longair,et al.  Optical spectra of 3CR radio galaxies. , 1979 .