On the 10-micron silicate feature in Active Galactic Nuclei

Abstract

The 10-micron silicate feature observed with Spitzer in active galactic nuclei (AGN) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped emission peaks shifted toward long wavelengths in several type 1 sources, and (3) is not seen in deep absorption in any source observed so far. We solve all three puzzles with our clumpy dust radiative transfer formalism. (1) We present the spectral energy distribution (SED) of SST1721+6012, the first type 2 quasar observed to show a clear 10-mic silicate feature in emission. We constructed a large database of clumpy torus models and performed extensive fitting of the observed SED, constraining several of the torus parameters. We find that the source bolometric luminosity is ~3*10^12 L_sun. Our modeling suggests that <35% of objects with tori sharing characteristics and geometry similar to the best fit would have their central engines obscured. This relatively low obscuration probability can explain the clear appearance of the 10-mic emission feature in SST1721+6012 together with its rarity among other QSO2. (2) We also fitted the SED of PG1211+143, one of the first type 1 QSOs with a 10-mic silicate feature in emission. Among similar sources, this QSO appears to display an unusually broadened feature whose peak is shifted toward longer wavelengths. Although this led to suggestions of non-standard dust chemistry in these sources, our analysis fits such SEDs with standard galactic dust; the apparent peak shifts arise from radiative transfer effects. (3) We find that the distribution of silicate feature strengths among clumpy torus models closely resembles the observed distribution, and the feature never occurs deeply absorbed. (abridged)

11 pages, 9 figures, 4 tables, accepted for publication in ApJ; minor revision, added reference in Section 1

References in corpus (10)

• AGN Dusty Tori: I. Handling of Clumpy Media
• Spitzer Quasar and ULIRG Evolution Study (QUEST): II. The Spectral Energy Distributions of Palomar-Green Quasars
• Optical spectroscopy and X-ray detections of a sample of quasars and AGN selected in the mid-infrared from two Spitzer wide-area surveys
• The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• Spitzer/IRS 5-35 um Low-Resolution Spectroscopy of the 12 um Seyfert Sample
• Silicates in Ultra-Luminous Infrared Galaxies
• Large amounts of optically-obscured star formation in the host galaxies of some type-2 quasars
• Extended silicate dust emission in PG QSOs
• The Origin of the Silicate Emission Features in the Seyfert 2 Galaxy, NGC 2110

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