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

We present the first near-infrared K -band long-baseline interferometric measurement of the nucleus of the prototype Seyfert 2 Galaxy NGC 1068 with resolution $\lambda/B \sim$ 10 mas obtained with the Very Large Telescope Interferometer (VLTI) and the two 8.2 m diameter Unit Telescopes UT 2 and UT 3. The adaptive optics system MACAO (Multi Application Curvature Adaptive Optics) was employed to deliver wavefront-corrected beams to the K -band commissioning instrument VINCI. A squared visibility amplitude of 16.3  ±  4.3% was measured for NGC 1068 at a sky-projected baseline length of 45.8 m and azimuth angle 44.9 deg. This value corresponds to a FWHM of the K -band intensity distribution of 5.0  ±  0.5 mas (0.4  ±  0.04 pc at the distance of NGC 1068) if it consists of a single Gaussian component. Taking into account K -band speckle interferometry observations (Wittkowski et al. [CITE]; Weinberger et al. [CITE]; Weigelt et al. [CITE]), we favor a multi-component model for the intensity distribution where a part of the flux originates from scales clearly smaller than ~5 mas ($\la$0.4 pc), and another part of the flux from larger scales. The K -band emission from the small ($\la$5 mas) scales might arise from substructure of the dusty nuclear torus, or directly from the central accretion flow viewed through only moderate extinction.

[1]  G. Perrin,et al.  A catalogue of calibrator stars for long baseline stellar interferometry , 2002 .

[2]  Bonn,et al.  From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs , 2003, astro-ph/0310329.

[3]  Mark R. Kidger,et al.  Spectral Irradiance Calibration in the Infrared. X. A Self-Consistent Radiometric All-Sky Network of Absolutely Calibrated Stellar Spectra , 1999 .

[4]  L. Danese,et al.  Thick tori around active galactic nuclei: a comparison of model predictions with observations of the infrared continuum and silicate features , 1994 .

[5]  Martin J. Ward,et al.  The polarization of NGC 1068. , 1988 .

[6]  Bonn,et al.  Where have all the black holes gone , 2002, astro-ph/0203489.

[7]  Karl-Heinz Hofmann,et al.  Interferometric studies of nearby galactic centers , 2003, SPIE Astronomical Telescopes + Instrumentation.

[8]  M. Rowan-Robinson,et al.  Dusty discs in active galactic nuclei , 1995 .

[9]  J. Bland-Hawthorn,et al.  The Ringberg Standards for NGC 1068 , 1997 .

[10]  R. Barvainis,et al.  Hot Dust and the Near-Infrared Bump in the Continuum Spectra of Quasars and Active Galactic Nuclei , 1987 .

[11]  Andreas Quirrenbach,et al.  The Nuclear Stellar Core, the Hot Dust Source, and the Location of the Nucleus of NGC 1068 , 1997 .

[12]  Robert Antonucci,et al.  Unified models for active galactic nuclei and quasars , 1993 .

[13]  Rainer Wilhelm,et al.  VINCI, the VLTI commissioning instrument: status after one year of operations at Paranal , 2003, SPIE Astronomical Telescopes + Instrumentation.

[14]  D. Segransan,et al.  Data reduction methods for single-mode optical interferometry Application to the VLTI two-telescopes beam combiner VINCI , 2004 .

[15]  Z. Ivezic,et al.  Dust Emission from Active Galactic Nuclei , 2002 .

[16]  Thierry Forveille,et al.  High angular resolution K-band spectroscopy of the nucleus of NGC 1068 with PUEO-GRIF (CFHT) , 2003 .

[17]  Julian H. Krolik,et al.  Infrared spectra of obscuring dust tori around active galactic nuclei. I - Calculational method and basic trends , 1992 .

[18]  J. Miller,et al.  Spectropolarimetry and the nature of NGC 1068 , 1985 .

[19]  Julian H. Krolik,et al.  Molecular tori in Seyfert galaxies - Feeding the monster and hiding it , 1988 .

[20]  Gerd Weigelt,et al.  Diffraction-limited bispectrum speckle interferometry of the nuclear region of the Seyfert galaxy NGC 1068 in the H and K' bands , 2004 .

[21]  M. Dopita,et al.  Probing the Dusty Accretion Torus of Seyfert Galaxies , 1998 .

[22]  G. Neugebauer,et al.  Diffraction-limited Imaging and Photometry of NGC 1068 , 1999 .

[23]  B. Krauskopf,et al.  Proc of SPIE , 2003 .

[24]  M.Swain,et al.  Interferometer Observations of Subparsec-Scale Infrared Emission in the Nucleus of NGC 4151 , 2003 .

[25]  Andreas Glindemann,et al.  VINCI: the VLT Interferometer commissioning instrument , 2000, Astronomical Telescopes and Instrumentation.

[26]  J. J. Bock,et al.  Draft version : ( ) document High Spatial Resolution Imaging of NGC 1068 in the Mid Infrared , 2022 .