ERRATUM: “AGN DUSTY TORI. II. OBSERVATIONAL IMPLICATIONS OF CLUMPINESS” (2008, ApJ, 685, 160)

Nenkova, Maia; Sirocky, M. M.; Nikutta, Robert; Ivezić, Željko; Elitzur, Moshe

doi:10.1088/0004-637x/723/2/1827

Cited by 374 publications

(729 citation statements)

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“…In particular, silicate emission features in type 1 AGN are much weaker than expected from early torus models, which used smooth dust distributions. As shown in the literature, this might be explained by clumpiness of the dust in the torus, which leads to an overall suppression of the emission feature (Nenkova et al 2002;Dullemond & van Bemmel 2005;Hönig et al 2006;Schartmann et al 2008;Nenkova et al 2008;Hönig & Kishimoto 2010). However, as will be shown in the second paper of this series (Hönig & Kishimoto 2010, pre-print available on astro-ph), weak emission features are not a generic property of clumpy torus models but might be used to constrain some model parameters of the dust distribution in clumpy tori.…”

Section: Introductionmentioning

confidence: 68%

The dusty heart of nearby active galaxies

Hoenig

Kishimoto

Gandhi

et al. 2010

A&A

154

135

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In a series of papers, we aim at stepping towards characterizing physical properties of the AGN dust torus by combining IR highspatial resolution observations with 3D clumpy torus models. In this first paper, we present mid-IR imaging and 8−13 μm lowresolution spectroscopy of nine type 1 and ten type 2 AGN. The observations were carried out with the VLT/VISIR mid-IR imager and spectrograph and can be considered the largest currently available mid-infrared spectro-photometric data set of AGN at spatial resolution < ∼ 100 pc. These data resolve scales at which the emission from the dust torus dominates the overall flux, and emission from the host galaxy (e.g. star-formation) is resolved out in most cases. The silicate absorption features are moderately deep and emission features, if seen at all, are shallow. The strongest silicate emission feature in our sample shows some notable shift of the central wavelength from the expected 9.7 μm (based on ISM extinction curves) to ∼10.5 μm. We compare the observed mid-IR luminosities of our objects to AGN luminosity tracers (X-ray, optical and [O iii] luminosities) and find that the mid-IR radiation is emitted quite isotropically. In two cases, IC 5063 and MCG-3-34-64, we find evidence for extended dust emission in the narrow-line region. We confirm the correlation between observed silicate feature strength and Hydrogen column density, which was recently found in Spitzer data at lower spatial resolution. In a further step, our 3D clumpy torus model has been used to interpret the data. We show that the strength of the silicate feature and the mid-IR spectral index α can be used to get reasonable constraints on the radial dust distribution of the torus and the average number of clouds N 0 along an equatorial line-of-sight in clumpy torus models. The mid-IR spectral index α is almost exclusively determined by the radial dust distribution power-law index a, while the silicate feature depth mostly depends on N 0 and the torus inclination. A comparison of model predictions to our type 1 and type 2 AGN reveals that average parameters of a = −1.0 ± 0.5 and N 0 = 5 − 8 are typically seen in the presented sample, which means that the radial dust distribution is rather shallow. As a proof-of-concept of this method, we compared the model parameters derived from α and the silicate feature strength to more detailed studies of full IR SEDs and interferometry and found that the constraints on a and N 0 are consistent. Finally, we may have found evidence that the radial structure of the torus changes from low to high AGN luminosities towards steeper dust distributions, and we discuss implications for the IR size-luminosity relation.

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Section: Introductionmentioning

confidence: 68%

The dusty heart of nearby active galaxies

Hoenig

Kishimoto

Gandhi

et al. 2010

A&A

154

135

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“…Monitoring results covering an even broader dynamical range of luminosity may be required to definitively rule out any of those alternative scenarios. Within the framework of our BLR model, we can also estimate the radial size of the BLR, assuming that it covers the region from the radius where T eff = 1000 K to the beginning of the dusty torus, R dust ∼ 0.4 L 1/2 45 pc (Nenkova et al 2008). The ratio of the two radii can be expressed in terms of the black hole mass, the accretion rate, and the accretion flow efficiency η (L bol = ηṀc 2 ) …”

Section: Discussionmentioning

confidence: 99%

The origin of the broad line region in active galactic nuclei

Czerny

Hryniewicz

2010

A&A

251

213

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Aims. Although broad emission lines are the most reliable signature of the nuclear activity of a galaxy and the location of the emitting material is well measured by the reverberation method, the physical cause of the formation of the broad line region remains unclear. We attempt to place some constraints on its origin. Methods. We study the properties of the accretion disk underlying the broad line region. Results. We find that the effective temperature at the disk radius corresponding to the location of the broad line region, as inferred from the Hβ line, is universal in all monitored sources and equal to 1000 K. This value is close to the limiting value that permits the existence of the dust. Conclusions. The likely origin of the low ionization part of the broad line region is the strong local dusty wind from the disk. This wind becomes exposed to the irradiation by the central regions when moving higher above the disk surface and subsequently behaves like a failed wind, thus leading to a local mixture of inflow and outflow. This may provide the physical explanation of the turbulence needed both to smooth the line profiles as well as provide additional mechanical heating.

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“…Since the seminal works about clumpy tori (Nenkova et al 2008) there is growing evidence against the monolithic obscurer envisaged by unified models Masini et al 2016;Marinucci et al 2016) of the Compton-thick clouds in the circumnuclear environment of NGC 4945. Fig.…”

Section: Clumpiness Of the Reflectormentioning

confidence: 99%

Spatially resolved Fe K spectroscopy of NGC 4945

Marinucci

Bianchi

Fabbiano

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the imaging and spectroscopic analysis of the combined Chandra ACIS-S observations of the Compton-thick Seyfert 2 galaxy NGC 4945. We performed a spatially-resolved spectroscopy of the circumnuclear environment of the source, picturing the innermost 200 parsecs around the highly absorbed nucleus. The additional 200 ks ACIS-S data with respect to the previous campaign allowed us to map with even greater detail the central structure of this source and to discover an enhanced iron emission in the innermost nuclear region, with respect to the associated Compton reflection continuum. We revealed that the Equivalent Width of the iron Kα line is spatially variable (ranging from 0.5 to 3 keV), on scales of tens of parsecs, likely due to the ionization state and orientation effects of the reprocessing material, with respect to the central X-ray illuminating source. A clump of highly ionized Fe xxv He-α is also detected, 40 parsecs east to the nucleus. When observations taken years apart are considered, the central unresolved reflected emission is found to remain constant.

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ERRATUM: “AGN DUSTY TORI. II. OBSERVATIONAL IMPLICATIONS OF CLUMPINESS” (2008, ApJ, 685, 160)

Cited by 374 publications

References 0 publications

The dusty heart of nearby active galaxies

The dusty heart of nearby active galaxies

The origin of the broad line region in active galactic nuclei

Spatially resolved Fe K spectroscopy of NGC 4945

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