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Title: MID-INFRARED SPECTROSCOPY OF HIGH-REDSHIFT 3CRR SOURCES

Abstract

Using the Spitzer Space Telescope, we have obtained rest-frame 9-16 {mu}m spectra of 11 quasars and 9 radio galaxies from the 3CRR catalog at redshifts 1.0 < z < 1.4. This complete flux-limited 178 MHz selected sample is unbiased with respect to orientation and therefore suited to studying orientation-dependent effects in the most powerful active galactic nuclei (AGNs). The mean radio-galaxy spectrum shows a clear silicate absorption feature ({tau}{sub 9.7{mu}m} = 1.1) whereas the mean quasar spectrum shows silicates in emission. The mean radio-galaxy spectrum matches a dust-absorbed mean quasar spectrum in both shape and overall flux level. The data for individual objects conform to these results. The trend of the silicate depth to increase with decreasing core fraction of the radio source further supports that for this sample orientation is the main driver for the difference between radio galaxies and quasars, as predicted by AGN unification. However, comparing our high-z sample with lower redshift 3CRR objects reveals that the absorption of the high-z radio galaxy MIR continuum is lower than expected from a scaled-up version of lower luminosity sources, and we discuss some effects that may explain these trends.

Authors:
;  [1]; ; ;  [2]; ; ; ;  [3];  [4];  [5];  [6]
  1. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
  2. Astronomisches Institut, Ruhr-Universitaet Bochum, Universitaetsstrasse 150, 44801 Bochum (Germany)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  4. Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen (Netherlands)
  5. European Southern Observatory, Karl-Schwarzschildstrasse 2, 85748 Garching (Germany)
  6. Spitzer Science Center, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
21455223
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 717; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/717/2/766; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABSORPTION SPECTROSCOPY; DUSTS; EMISSION; GALAXY NUCLEI; INFRARED SPECTRA; LUMINOSITY; QUASARS; RADIO GALAXIES; RED SHIFT; SILICATES; TELESCOPES; COSMIC RADIO SOURCES; GALAXIES; OPTICAL PROPERTIES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SILICON COMPOUNDS; SORPTION; SPECTRA; SPECTROSCOPY

Citation Formats

Leipski, C, Antonucci, R, Haas, M, Chini, R, Heymann, F, Willner, S P, Ashby, M L. N., Wilkes, B J, Fazio, G G, Barthel, P, Siebenmorgen, R, and Ogle, P. MID-INFRARED SPECTROSCOPY OF HIGH-REDSHIFT 3CRR SOURCES. United States: N. p., 2010. Web. doi:10.1088/0004-637X/717/2/766.
Leipski, C, Antonucci, R, Haas, M, Chini, R, Heymann, F, Willner, S P, Ashby, M L. N., Wilkes, B J, Fazio, G G, Barthel, P, Siebenmorgen, R, & Ogle, P. MID-INFRARED SPECTROSCOPY OF HIGH-REDSHIFT 3CRR SOURCES. United States. https://doi.org/10.1088/0004-637X/717/2/766
Leipski, C, Antonucci, R, Haas, M, Chini, R, Heymann, F, Willner, S P, Ashby, M L. N., Wilkes, B J, Fazio, G G, Barthel, P, Siebenmorgen, R, and Ogle, P. 2010. "MID-INFRARED SPECTROSCOPY OF HIGH-REDSHIFT 3CRR SOURCES". United States. https://doi.org/10.1088/0004-637X/717/2/766.
@article{osti_21455223,
title = {MID-INFRARED SPECTROSCOPY OF HIGH-REDSHIFT 3CRR SOURCES},
author = {Leipski, C and Antonucci, R and Haas, M and Chini, R and Heymann, F and Willner, S P and Ashby, M L. N. and Wilkes, B J and Fazio, G G and Barthel, P and Siebenmorgen, R and Ogle, P},
abstractNote = {Using the Spitzer Space Telescope, we have obtained rest-frame 9-16 {mu}m spectra of 11 quasars and 9 radio galaxies from the 3CRR catalog at redshifts 1.0 < z < 1.4. This complete flux-limited 178 MHz selected sample is unbiased with respect to orientation and therefore suited to studying orientation-dependent effects in the most powerful active galactic nuclei (AGNs). The mean radio-galaxy spectrum shows a clear silicate absorption feature ({tau}{sub 9.7{mu}m} = 1.1) whereas the mean quasar spectrum shows silicates in emission. The mean radio-galaxy spectrum matches a dust-absorbed mean quasar spectrum in both shape and overall flux level. The data for individual objects conform to these results. The trend of the silicate depth to increase with decreasing core fraction of the radio source further supports that for this sample orientation is the main driver for the difference between radio galaxies and quasars, as predicted by AGN unification. However, comparing our high-z sample with lower redshift 3CRR objects reveals that the absorption of the high-z radio galaxy MIR continuum is lower than expected from a scaled-up version of lower luminosity sources, and we discuss some effects that may explain these trends.},
doi = {10.1088/0004-637X/717/2/766},
url = {https://www.osti.gov/biblio/21455223}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 717,
place = {United States},
year = {Sat Jul 10 00:00:00 EDT 2010},
month = {Sat Jul 10 00:00:00 EDT 2010}
}