A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies
By L. Burtscher, K. Meisenheimer, K. Tristram, W. Jaffe, S. Honig, Roger Davies, M. Kishimoto, J. Pott, H. Rottgering, M. Schartmann and 2 more. 2013
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The AGN-heated dust distribution (the "torus") is increasingly recognized not only as the absorber required in unifying models, but as a tracer for the reservoir that feeds the nuclear Super-Massive Black Hole. Yet, even its most basic structural properties (such as its extent, geometry and elongation) are unknown for all but a few archetypal objects. Since most AGNs are unresolved in the mid-infrared, we utilize the MID-infrared interferometric Instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) that is sensitive to structures as small as a few milli-arcseconds (mas). We present here an extensive amount of new interferometric observations from the MIDI AGN Large Program (2009 - 2011) and add data from the archive to give a complete view of the existing MIDI observations of AGNs. Additionally, we have obtained high-quality mid-infrared spectra from VLT/VISIR. We present correlated and total flux spectra for 23 AGNs and derive flux and size estimates at 12 micron using simple axisymmetric geometrical models. Perhaps the most surprising result is the relatively high level of unresolved flux and its large scatter: The median "point source fraction" is 70 % for type 1 and 47 % for type 2 AGNs meaning that a large part of the flux is concentrated on scales smaller than about 5 mas (0.1 - 10 pc). Among sources observed with similar spatial resolution, it varies from 20 % - 100 %. For 18 of the sources, two nuclear components can be distinguished in the radial fits. While these models provide good fits to all but the brightest sources, significant elongations are detected in eight sources. The half-light radii of the fainter sources are smaller than expected from the size ~ L^0.5 scaling of the bright sources and show a large scatter, especially when compared to the relatively tight size--luminosity relation in the near-infrared.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/2cf04bcb60877525cb1a961f891318925affa92c
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Citations in the corpus
- Formation and Evolution of Compact-object Binaries in AGN Disks (2019, background): “Mid-infrared observations show that the sizes of AGN disks are ~ ~r L M f pc 10 erg 0.1 pc 0.03 75AGN bol 45 1 2 SgrA 1 2 Edd 1 2 ( ) ⎛ ⎝⎜ ⎞ ⎠⎟ ⎛ ⎝⎜ ⎞ ⎠⎟ (see Figure 36 in Burtscher et al. 2013), where Lbol is the bolometric luminosity of an AGN disk.”
- New Spectral Model for Constraining Torus Covering Factors from Broadband X-Ray Spectra of Active Galactic Nuclei (2018, background): “Infrared photometry and spectroscopy at high spatial resolution (Ichikawa et al. 2015), interferometry (Burtscher et al. 2013) and polarimetry (Lopez-Rodriguez et al. 2015) have significantly contributed to recent advances in probing AGN structures.”
- Molecular line emission in NGC 1068 imaged with ALMA: I. An AGN-driven outflow in the dense molecular gas (2014, methodology): “For comparison the modeled 12 µm interferometric half radius of the resolved and unresolved components of NGC 1068 is 1.6 pc (Burtscher et al. 2013).”
- The subarcsecond mid-infrared view of local active galactic nuclei – I. The N- and Q-band imaging atlas (2013, methodology): “This method is quite commonly used in MIR interferometric data (e.g., Burtscher et al. 2013) to disentangle extended emission and the central engine.”
- X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue (2014, background): “This picture is further motivated by high-resolution optical space-based observations (Ferrarese et al. 1996; van der Marel & van den Bosch 1998), which show such a toruslike structures in ∼ 100−1000pc scale, or more recently, mid-infrared interferometry (Burtscher et al. 2013).”
- Assisted inspirals of stellar mass black holes embedded in AGN discs: solving the ‘final au problem’ (2016, background): “10 pc (Burtscher et al. 2013), motivating our fiducial choice of Rout = 10 pc: if the reader is curious about disks truncated at smaller radii, our results can be simply cut off beyond the desired radius (disk conditions in the T05 model do not depend on conditions exterior to the radius of…”
- Revisiting the Unified Model of Active Galactic Nuclei (2015, methodology): “(adopted from Burtscher et al. (2013), courtesy of Leonard Burtscher).”
- Cosmic X-ray surveys of distant active galaxies (2015, background): “In recent years, for example, it has become possible to obtain direct estimates of the (luminosity dependent) extent of the torus (e.g., Burtscher et al 2013; Koshida et al 2014) and to ascertain its apparently clumpy nature (e.g., Elitzur and Shlosman 2006; Mor et al 2009).”
- The dusty torus in the Circinus galaxy: a dense disk and the torus funnel (2013, background): “The correlation losses should instead be a smooth function of wavelength and only become significant for Fcor(12 μm) < 150 mJy (Burtscher et al. 2013).”