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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.

Context. We present high-spatial and medium-spectral resolution imaging and spectroscopy of the core of the Seyfert II galaxy NGC 1068, obtained in the N-band spectral range with the VLT/VISIR (the VLT Imager and Spectrometer in the InfraRed). Spectra were acquired in the ArIII 8.99 µm, SIV 10.51 µm and NeII 12.81 µm filters for two orientations of the long slit (2 × 0. 4): PA = −15• and 90• oriented N to E. Aims. The spatial evolution of the [ArIII]+[MgVII], [SIV] and [NeII] lines are investigated to constrain the gas dynamics inside the narrow line region (NLR), and to deduce the geometry and physics of the ionization cones. Methods. Spectra are extracted in 0. 381 steps along the two slit positions and we obtain line parameters from fits with Gaussian profiles. The computed line ratios are compared to photoionization models. Results. Lines are resolved and detected in emission up to ∼3 NW and ∼3 SE of the core, generally double-peaked. Features trace an outflow with radial velocities up to 10 3 km s −1 , well reproduced by a hollow biconical structure associated with the ionization bicone of NGC 1068. It is inclined at ∼11• and the maximum aperture is ∼80• , in good agreement with optical spectroscopic studies. Conclusions. The velocity profiles traced in the MIR are interpreted as evidence for a gas outflow along the edges of the ionization bicones. The comparison of line ratios with standard dust-free and dusty, radiation pressure-dominated photoionization models shows that the associated gas metallicity is close to the solar value and points to a relatively weak ionization parameter of a typical value U 0 = 10 −2.6 at PA = −15• along the ionization bicone.

Very-High Energy (VHE) gamma-ray astroparticle physics is a relatively young field, and observations over the past decade have surprisingly revealed almost two hundred VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known -such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming observatory from its design to the construction, and its potential science exploitation. CTAO will allow the entire astronomical community to explore a new discovery space that will likely lead to paradigm-changing breakthroughs. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, placing it as a key instrument in the future of multi-messenger and multi-wavelength time domain astronomy. I will conclude the talk presenting the first scientific results obtained by the LST-1, the prototype of one CTA telescope type -the Large Sized Telescope, that is currently under commission.

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