QUANTIFYING THE ANISOTROPY IN THE INFRARED EMISSION OF POWERFUL ACTIVE GALACTIC NUCLEI
- Department of Physics, University of California in Santa Barbara, Broida Hall, Santa Barbara, CA 93109 (United States)
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)
- 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, Vol. 736, Issue 1; Other Information: DOI: 10.1088/0004-637X/736/1/26; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE NUCLEAR INFRARED EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI
THE INFRARED NUCLEAR EMISSION OF SEYFERT GALAXIES ON PARSEC SCALES: TESTING THE CLUMPY TORUS MODELS