Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies
| Autor: | Jack F. Gallimore, R. C. Gleisinger, C. P. O'Dea, Stefi A. Baum, S. Wykes |
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| Rok vydání: | 2020 |
| Předmět: |
Active galactic nucleus
010504 meteorology & atmospheric sciences Infrared Radio galaxy Astrophysics::High Energy Astrophysical Phenomena media_common.quotation_subject FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Emission spectrum 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences media_common Physics Astronomy and Astrophysics Torus Astrophysics - Astrophysics of Galaxies Galaxy Photometry (astronomy) 13. Climate action Space and Planetary Science Sky Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Earth and Planetary Astrophysics |
| Zdroj: | The Astrophysical Journal. 905:42 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.3847/1538-4357/abc332 |
| Popis: | How do active galactic nuclei with low optical luminosities produce powerful radio emission? Recent studies of active galactic nuclei with moderate radio and low optical luminosities (Fanaroff & Riley class I, FR I) searching for broad nuclear emission lines in polarized light, as predicted by some active galactic nucleus unification models, have found heterogeneous results. These models typically consist of a central engine surrounded by a torus of discrete dusty clouds. These clouds would absorb and scatter optical emission, blocking broad nuclear emission lines, and reradiate in mid-infrared. Some scattered broad-line emission may be observable, depending on geometry, which would be polarized. We present a wide-band infrared spectroscopic analysis of 10 nearby FR I radio galaxies to determine whether there is significant emission from a dusty obscuring structure. We used Markov Chain Monte Carlo algorithms to decompose Spitzer/IRS spectra of our sample. We constrained the wide-band behavior of our models with photometry from the Two Micron All Sky Survey, Spitzer/IRAC, Spitzer/MIPS, and Herschel/SPIRE. We find that one galaxy is best fit by a clumpy torus and three others show some thermal mid-infrared component. This suggests that in those three there is likely some obscuring dust structure that is inconsistent with our torus models and there must be some source of photons heating the dust. We conclude that 40% of our FR I radio galaxies show evidence of obscuring dusty material, possibly some other form of hidden broad-line nucleus, but only 10% favor the clumpy torus model specifically. |
| Databáze: | OpenAIRE |
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