The mineralogy of newly formed dust in active galactic nuclei

Abstract

The tori around active galactic nuclei (AGN) are potential formation sites for large amounts of dust, and they may help resolve the so-called dust budget crisis at high redshift. We investigate the dust composition in 53 of the 87 Palomar Green (PG) quasars showing the 9.7 micron silicate feature in emission. By simultaneously fitting the mid-infrared spectroscopic features and the underlying continuum, we estimate the mass fraction in various amorphous and crystalline dust species. We find that the dust consists predominantly of alumina and amorphous silicates, with a small fraction in crystalline form. The mean crystallinity is 8 +/- 6%, with more than half of the crystallinities greater than 5%, well above the upper limit determined for the Galaxy. Higher values of crystallinity are found for higher oxide fractions and for more luminous sources.

arXiv comment24 pages, 9 figures, accepted for publication in Planetary and Space Science

References in corpus (49)

• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• Revisiting the Unified Model of Active Galactic Nuclei
• Revisiting the Infrared Spectra of Active Galactic Nuclei with a New Torus Emission Model
• The absence of crystalline silicates in the diffuse interstellar medium
• The AGN Obscuring Torus -- End of the "Doughnut" Paradigm?
• Dust Emission from Active Galactic Nuclei
• Spitzer Quasar and ULIRG Evolution Study (QUEST). IV. Comparison of 1-Jy Ultraluminous Infrared Galaxies with Palomar-Green Quasars
• Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium
• The CH out-of-plane bending modes of PAH molecules in astrophysical environments
• Non-linear Least Squares Fitting in IDL with MPFIT
• Modeling optical properties of cosmic dust grains using a distribution of hollow spheres
• Spitzer Quasar and ULIRG Evolution Study (QUEST): II. The Spectral Energy Distributions of Palomar-Green Quasars
• CASSIS: The Cornell Atlas of Spitzer/IRS Sources
• What controls the C IV line profile in active galactic nuclei?
• Radiative Transfer Modeling of Three-Dimensional Clumpy AGN Tori and its Application to NGC 1068
• Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the far infrared continuum of QSOs
• On Ultrasmall Silicate Grains in the Diffuse Interstellar Medium
• The Detection of Silicate Emission from Quasars at 10 and 18 Microns
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• 9.7 um Silicate Features in AGNs: New Insights into Unification Models
• Spatially-resolved mid-infrared spectroscopy of NGC 1068: the nature and distribution of the nuclear material
• Smoking Quasars: a New Source for Cosmic Dust
• AGN Obscuration and the Unified Model
• Silicate emissions in active galaxies - From LINERs to QSOs
• On the 10-micron silicate feature in Active Galactic Nuclei
• The Origins of AGN Obscuration: The 'Torus' as a Dynamical, Unstable Driver of Accretion
• CASSIS: The Cornell Atlas of Spitzer/Infrared Spectrograph Sources. II. High-resolution observations
• Revealing the large nuclear dust structures in NGC 1068 with MIDI/VLTI
• A mid-infrared spectroscopic atlas of local active galactic nuclei on sub-arcsecond resolution using GTC/CanariCam
• A new analysis of the nucleus of NGC 1068 with MIDI observations
• On the Crystallinity of Silicate Dust in the Interstellar Medium
• New radiative transfer models for obscuring tori in active galaxies
• Infrared spectra and photometry of complete samples of PG and 2MASS quasars
• A complete census of silicate features in the mid-infrared spectra of active galaxies
• Dust in the wind: Crystalline silicates, corundum and periclase in PG 2112+059
• Herschel Survey of the Palomar-Green QSOs at Low Redshift
• Anomalous Silicate Dust Emission in the Type 1 LINER Nucleus of M81
• Sweeping Away the Mysteries of Dusty Continuous Winds in AGN
• The First Spatially Resolved Mid-IR Spectra of NGC 1068 Obtained at Diffraction-limited Resolution with LWS at Keck I Telescope
• The Compton-Thick Seyfert 2 Nucleus of NGC3281: Torus Constraints from the 9.7$\mu$m Silicate Absorption
• Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068
• The underlying driver for the \civ Baldwin effect in QSOs with $0<z<5$
• On the Anomalous Silicate Absorption Feature of the Prototypical Seyfert 2 Galaxy NGC 1068
• On the Anomalous Silicate Emission Features of AGNs: A Possible Interpretation Based on Porous Dust
• A Tale of Three Galaxies: Anomalous Dust Properties in IRASF10398+1455, IRASF21013-0739 and SDSSJ0808+3948
• Dust in the Torus of the AGN Unified Model
• Large Radio Telescopes for Anomalous Microwave Emission Observations
• A Tale of Three Galaxies: Deciphering the Infrared Emission of the Spectroscopically Anomalous Galaxies IRAS F10398+1455, IRAS F21013-0739 and SDSS J0808+3948

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• The dust-gas AGN torus as constrained from X-ray and mid-infrared observations
• Modelling the strongest silicate emission features of local type 1 AGN
• Dust formation in AGN winds
• The role of grain size in AGN torus dust models
• Modelling the evolution and influence of dust in cosmological simulations that include the cold phase of the interstellar medium
• A systematic study of silicate absorption features in heavily obscured AGNs observed by Spitzer/IRS
• Towards an observationally motivated AGN dusty torus model -- II. The roles of density distribution and chemical composition of the dust
• Cosmic Dust IX