Spitzer Reveals Hidden Quasar Nuclei in Some Powerful FR II Radio Galaxies
| dc.creator | Ogle, P. M. | |
| dc.creator | Whysong, D. | |
| dc.creator | Antonucci, R. | |
| dc.date | 2006-01-20 | |
| dc.date.accessioned | 2026-07-07T10:43:34Z | |
| dc.date.available | 2026-07-07T10:43:34Z | |
| dc.description | We present a Spitzer mid-infrared survey of 42 Fanaroff-Riley class II radio galaxies and quasars from the 3CRR catalog at redshift z<1. All of the quasars and 45+/-12% of the narrow-line radio galaxies have a mid-IR luminosity of nuLnu(15 micron) > 8E43 erg/s, indicating strong thermal emission from hot dust in the active galactic nucleus. Our results demonstrate the power of Spitzer to unveil dust-obscured quasars. The ratio of mid-IR luminous narrow-line radio galaxies to quasars indicates a mean dust covering fraction of 0.56+/-0.15, assuming relatively isotropic emission. We analyze Spitzer spectra of the 14 mid-IR luminous narrow-line radio galaxies thought to host hidden quasar nuclei. Dust temperatures of 210-660 K are estimated from single-temperature blackbody fits to the low and high-frequency ends of the mid-IR bump. Most of the mid-IR luminous radio galaxies have a 9.7 micron silicate absorption trough with optical depth <0.2, attributed to dust in a molecular torus. Forbidden emission lines from high-ionization oxygen, neon, and sulfur indicate a source of far-UV photons in the hidden nucleus. However, we find that the other 55+/-13% of narrow-line FR II radio galaxies are weak at 15 micron, contrary to single-population unification schemes. Most of these galaxies are also weak at 30 micron. Mid-IR weak radio galaxies may constitute a separate population of nonthermal, jet-dominated sources with low accretion power | |
| dc.description | 34 pages, 8 figures, ApJ submitted | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0601485 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0601485 | |
| dc.identifier | Astrophys.J.647:161-171,2006 | |
| dc.identifier | doi:10.1086/505337 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/182284 | |
| dc.subject | Astrophysics | |
| dc.title | Spitzer Reveals Hidden Quasar Nuclei in Some Powerful FR II Radio Galaxies | |
| dc.type | text |