VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive optics system MACAO

Wittkowski, M.; Kervella, P.; Arsenault, Robin; Paresce, Francesco; Beckert, T.; Weigelt, G.

doi:10.1051/0004-6361:20040118

Cited by 99 publications

(107 citation statements)

References 30 publications

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“…Over the last few years, using AO for NIR observations, it has become possible to probe these objects at 100mas scales. MIR interferometry has now resolved the dusty torus for ~10 AGN and even more detailed views were possible for NGC 1068 [23], [24] and NGC 4151 [25]. GRAVITY will continue that route to smaller angular sizes.…”

Section: Active Galactic Nucleimentioning

confidence: 97%

GRAVITY: getting to the event horizon of Sgr A*

et al. 2008

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We present the second-generation VLTI instrument GRAVITY, which currently is in the preliminary design phase. GRAVITY is specifically designed to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We have identified the key design features needed to achieve this goal and present the resulting instrument concept. It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near infrared wavefront sensing adaptive optics; fringe tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that the planned design matches the scientific needs; in particular that 10µas astrometry is feasible for a source with a magnitude of K=15 like Sgr A*, given the availability of suitable phase reference sources.

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Section: Active Galactic Nucleimentioning

confidence: 97%

GRAVITY: getting to the event horizon of Sgr A*

et al. 2008

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“…The most promising tool for this task is IR interferometry, which was already successfully used for a number of nearby objects (Swain et al 2003;Wittkowski et al 2004;Weigelt et al 2004;Jaffe et al 2004;Poncelet et al 2006;Meisenheimer et al 2007;Tristram et al 2007Tristram et al , 2009Beckert et al 2008;Raban et al 2009;Burtscher et al 2009;Kishimoto et al 2009b). However, except for reconstructed images of NGC 1068 obtained from Speckle interferometry (Weigelt et al 2004), long-baseline interferometry usually provides spatial information coded as Fourier space observables, i.e.…”

Section: Interferometry Of Dust Torimentioning

confidence: 99%

The dusty heart of nearby active galaxies

Hönig

Kishimoto

2010

A&A

200

221

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With the possibilities of high spatial resolution imaging and spectroscopy as well as infrared (IR) interferometry, the dusty environments (= "dusty torus") of active galactic nuclei (AGN) are now in reach of observations. Following our Paper I on ground-based mid-IR spectro-photometry, we present an upgrade to our radiative transfer model of three-dimensional clumpy dust tori. The upgrade with respect to earlier work concerns an improved handling of the diffuse radiation field in the torus, which is approximated by a statistical approach. The models are presented as tools to translate classical and interferometric observations into characteristic properties of the dust distribution. We compare model spectral energy distributions (SEDs) for different chemical and grain-size compositions of the dust and find that clouds with standard interstellar matter (ISM) dust and optical depth τ V ∼ 50 appear in overall agreement with observed IR SEDs. By studying parameter dependencies, it is shown that type 1 AGN SEDs, in particular the mid-IR spectral index, can be used to constrain the radial dust cloud distribution power law index a, while other parameters are more difficult to assess using SEDs only. Interferometry adds important additional information for modeling when it is interpreted concurrently with the SED. Although type 2 AGN can in principle be used to constrain model parameters as well, obscuration effects make the analysis more ambiguous. We propose a simple, interferometry-based method to distinguish between "compact" and "extended" radial dust distributions without detailed modeling of the data and introduce a way to easily determine individual or sample average model parameters using the observed optical depth in the silicate feature and the mid-IR spectral index.

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“…Speckle imaging from the Keck Observatory also showed that the flux emitted by the core of the AGN may be accounted for by an unresolved point source whose size is smaller than ∼20 mas and which is surrounded by an emitting region extending up to 10 pc (Weinberger et al 1999). Wittkowski et al (2004) combined near-IR speckle data with the K-band visibility point obtained with VINCI and interpreted the whole dataset with a two-component model: a small one having a size of ∼5 mas (or 0.4 pc) responsible for 40% of the K-band flux and an extended one of ∼40 mas. In addition, near-IR bispectrum speckle interferometric observations led to a N-W extended structure in K -band having a size of 39×18 mas and a PA ∼ −16 • (Weigelt et al 2004).…”

Section: Spatial Description Of the Sourcementioning

confidence: 99%

A new analysis of the nucleus of NGC 1068 with MIDI observations

Poncelet

Perrin²,

Sol³

2006

A&A

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We present a new analysis of the first mid-infrared N-band long-baseline interferometric observations of an extragalactic source: the nucleus of the Seyfert 2 galaxy NGC 1068, obtained with MIDI (Mid-InfrareD Interferometer), the mid-infrared beamcombiner at the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). The resolution of λ/B ∼ 10 mas allows us to study the compact central core of the galaxy between 8 and 13 µm. Both visibility measurements and MIDI spectrum are well reproduced by a simple radiative transfer model with two concentric spherical components. The derived angular sizes and temperatures are ∼35 and 83 mas, and ∼361 K and 226 K for these two components respectively. Other evidence strongly supports such low temperatures. This modeling also provides the variation of optical depth as a function of wavelength for the extended component across the N-band suggesting the presence of amorphous silicate grains. This shows that MIDI has carried out the first direct observations of the distribution of dust around the central engine.

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VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive optics system MACAO

Cited by 99 publications

References 30 publications

GRAVITY: getting to the event horizon of Sgr A*

GRAVITY: getting to the event horizon of Sgr A*

The dusty heart of nearby active galaxies

A new analysis of the nucleus of NGC 1068 with MIDI observations

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