Related papers: Dust in Active Galactic Nuclei: Anomalous Silicate…
Dust plays a central role in the unification theory of active galactic nuclei (AGNs). Whether the dust that forms the torus around an AGN is tenth-$\mu$m-sized like interstellar grains or much larger has a profound impact on correcting for…
The unification theory of active galactic nuclei (AGNs) hypothesizes that all AGNs are surrounded by an anisotropic dust torus and are essentially the same objects but viewed from different angles. However, little is known about the dust…
We present observational evidences that dust in the circumnuclear region of AGNs has different properties than in the Galactic diffuse interstellar medium. By comparing the reddening of optical and infrared broad lines and the X-ray…
Dust plays an essential role in the unification theory of active galactic nuclei (AGNs). This review summarizes our current understanding of the extinction and infrared emission properties of the circumnuclear dust in AGNs as well as the…
We report the detection of a 9.7 $\mu$m silicate dust absorption feature toward the Cygnus A nucleus. Its optical depth is, however, significantly smaller than that expected from the dust extinction toward the background $L$-band emission…
In a companion paper, Maiolino et al. (2000) presented various observational evidences for "anomalous" dust properties in the circumnuclear region of AGNs and, in particular, the reduced E(B-V)/N_H and Av/N_H ratios, the absence of the…
We quantify the luminosity contribution of active galactic nuclei (AGN) to the 12 $\mu$m, mid-infrared (MIR; 5-38 $\mu$m), and the total IR (5-1000 $\mu$m) emission in the local AGN detected in the all-sky 70-month Swift/Burst Alert…
The recent Spitzer detections of the 9.7 micron Si--O silicate emission in type 1 AGNs provide support for the AGN unification scheme. The properties of the silicate dust are of key importance to understanding the physical, chemical and…
Heavily obscured active galactic nuclei (AGNs) are known to show deep silicate absorption features in the mid-infrared (IR) wavelength range of 10--20~$\mu$m. The detailed profiles of the features reflect the properties of silicate dust,…
The primary source of emission of active galactic nuclei (AGN), the accretion disk, is surrounded by an optically and geometrically thick dusty structure ("the so-called dusty torus"). The infrared radiation emitted by the dust is nothing…
Type 2 AGN are by definition nuclei in which the broad-line region and continuum light are hidden at optical/UV wavelengths by dust. Via accurate registration of infrared (IR) Very Large Telescope adaptive optics images with optical…
We explore the origin of mid-infrared (mid-IR) dust extinction in all 20 nearby (z < 0.05) bona-fide Compton-thick (N_H > 1.5 x 10^24 cm^-2) AGN with hard energy (E > 10 keV) X-ray spectral measurements. We accurately measure the silicate…
We describe improved modelling of the emission by dust in a toroidal--like structure heated by a central illuminating source within Active Galactic Nuclei (AGN). We chose a simple but realistic torus geometry, a flared disc, and a dust…
We use mid-infrared spectroscopy of unobscured active galactic nuclei (AGNs) to reveal their native dusty environments. We concentrate on Seyfert 1 galaxies, observing a sample of 31 with the Infrared Spectrograph aboard the Spitzer Space…
A parsec-scale dusty torus is thought to be the cause of Active Galactic Nuclei (AGN) dichotomy in the 1/2 types, narrow/broad emission lines. In a previous work, on the basis of parsec-scale resolution infrared / optical dust maps it was…
The presence of the dust in the circumnuclear region strongly affects our view of the nucleus itself. The effect is strong in type 2 objects but weaker effect is likely to be present in type 1 objects as well. In these objects a correction…
We present Spitzer IRS low resolution, mid-IR spectra of a sample of 25 high luminosity QSOs at 2<z<3.5. When combined with archival IRS observations of local, low luminosity type-I AGNs, the sample spans five orders of magnitude in…
Approximately 3-17 percent of Active Galactic Nuclei (AGN) without detected rest-frame UV/optical broad emission lines (type-2 AGN) do not show absorption in X-rays. The physical origin behind the apparently discordant optical/X-ray…
Extinction curves observed toward individual Active Galactic Nuclei (AGN) usually show a steep rise toward far-ultraviolet (FUV) wavelengths and can be described by the Small Magellanic Cloud (SMC)-like dust model. This feature suggests the…
Unified schemes of active galactic nuclei (AGN) require an obscuring dusty torus around the central source, giving rise to Seyfert 1 line spectrum for pole-on viewing and Seyfert 2 characteristics in edge-on sources. Although the observed…