QUANTIFYING THE ANISOTROPY IN THE INFRARED EMISSION OF POWERFUL ACTIVE GALACTIC NUCLEI

Journal Article · Wed Jul 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/736/1/26· OSTI ID:21578344

Hoenig, S F; Antonucci, R ^[1]; Leipski, C ^[2]; Haas, M ^[3]

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1. Department of Physics, University of California in Santa Barbara, Broida Hall, Santa Barbara, CA 93109 (United States)
2. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)
3. Astronomisches Institut RuhrUniversitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany)

We use rest-frame near- and mid-IR data of an isotropically selected sample of quasars and radio galaxies at 1.0 {<=} z {<=} 1.4, which have been published previously by Leipski et al., to study the wavelength-dependent anisotropy of the IR emission. For that we build average spectral energy distributions of the quasar subsample (= type 1 AGNs) and radio galaxies (= type 2 AGNs) from {approx}1 to 17 {mu}m and plot the ratio of both average samples. From 2 to 8 {mu}m rest-frame wavelengths the ratio gradually decreases from 20 to 2 with values around 3 in the 10 {mu}m silicate feature. Longward of 12 {mu}m, the ratio decreases further and shows some high degree of isotropy at 15 {mu}m (ratio {approx}1.4). The results are consistent with upper limits derived from the X-ray/mid-IR correlation of local Seyfert galaxies. We find that the anisotropy in our high-luminosity radio-loud sample is smaller than in radio-quiet lower-luminosity active galactic nuclei (AGNs) which may be interpreted in the framework of a receding torus model with luminosity-dependent obscuration properties. It is also shown that the relatively small degree of anisotropy is consistent with clumpy torus models.

• OSTI ID: 21578344
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 736; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
EMISSION
ENERGY SPECTRA
GALAXIES
GALAXY NUCLEI
INFRARED RADIATION
QUASARS
RADIATIONS
RADIO GALAXIES
SEYFERT GALAXIES
SPECTRA
WAVELENGTHS