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We report ALMA observations of CO(3-2) emission in the Seyfert2/starburst galaxy NGC1808, at a spatial resolution of 4pc. Our aim is to investigate the morphology and dynamics of the gas inside the central 0.5kpc, and to probe nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 1=45pc and inside it a decoupled circumnuclear disk, or molecular torus of radius 0.13=6pc. The HCN(4-3) and HCO$rm^+$(4-3) and CS(7-6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and present the same misalignment in the molecular torus. At the nucleus the HCN/HCO$^+$ and HCN/CS ratios indicate the presence of an AGN. The molecular gas shows regular rotation, within a radius of 400pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 50pc is feeding the nucleus, on a time-scale of $sim$60Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow due to the AGN feedback. The molecular outflow detected at $geqslant$250pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc scale superwind.
The hypervelocity stars recently found in the Galactic halo are expelled from the Galactic center through interactions between binary stars and the central massive black hole or between single stars and a hypothetical massive binary black hole. In th
We present a harmonic expansion of the observed line-of-sight velocity field as a method to recover and investigate spiral structures in the nuclear regions of galaxies. We apply it to the emission-line velocity field within the circumnuclear starfor
Warm absorbers are found in many AGN and consist of clouds moving at moderate radial velocities, showing complex ionization structures and having moderate to large column densities. Using 1D numerical calculations, we confirm earlier suggestions that
Feedback from an active galactic nucleus (AGN) is often implicated as a mechanism that leads to the quenching of galactic star formation. However, AGN-driven quenching is challenging to reconcile with observations that AGN hosts tend to harbour equal
Pre-DECIGO consists of three spacecraft arranged in an equilateral triangle with 100km arm lengths orbiting 2000km above the surface of the earth. It is hoped that the launch date will be in the late 2020s. Pre-DECIGO has one clear target: binary b