We employ MUSE/VLT data to study the ionised and highly ionised gas phases of the feedback in Circinus, the closest Seyfert 2 galaxy to us. The analysis of the nebular emission allowed us to detect a remarkable high-ionisation gas outflow beyond the galaxy plane traced by the coronal lines [Fe vii] λ6089 and [Fe x] λ6374, extending up to 700 pc and 350 pc NW from the nucleus, respectively. This is the first time that the [Fe x] emission is observed at such distances from the central engine in an AGN. The gas kinematics reveals expanding gas shells with velocities of a few hundred  km s−1, spatially coincident with prominent hard X-ray emission detected by Chandra. Density and temperature sensitive line ratios show that the extended high-ionisation gas is characterized by a temperature reaching 25000 K and an electron density >102 cm−3 . We found that local gas excitation by shocks produced by the passage of a radio jet leads to the spectacular high-ionisation emission in this object. This hypothesis is fully supported by photoionisation models that accounts for the combined effects of the central engine and shocks. They reproduce the observed emission line spectrum at different locations inside and outside of the NW ionisation cone. The energetic outflow produced by the radio jet is spatially located close to an extended molecular outflow recently reported using ALMA which suggests that they both represent different phases of the same feedback process acting on the AGN.

In this contribution, we present the first numerical simulations of a relativistic outflow propagating through the inner hundreds of parsecs of its host galaxy, including atomic and ionized hydrogen, and the cooling effects of ionization.Our results are preliminary, but we observe efficient shock ionization of atomic hydrogen in interstellar clouds. The mean density of the interstellar medium in these initial simulations is lower than that expected in typical galaxies, which makes cooling times longer and thus no recombination is observed inside the shocked region. The velocities achieved by the shocked gas in the simulations are in agreement with observational results, although with a wide spectrum of values.

We present new Gemini spectroscopical data of the extended emission-line region of the 3C 305 radio galaxy in order to achieve a final answer to the long-standing question about the ionizing mechanism. The spectra show strong kinematic disturbances within the most intense line-emitting region. The relative intensities of the emission lines agree with the hypothesis that the gas is shocked during the interaction of powerful radio jets with the ambient medium. The emission from the recombination region acts as a very effective cooling mechanism, which is supported by the presence of a neutral outflow. However, the observed intensity is almost an order of magnitude lower than expected in a pure shock model. So, autoionizing shock models, in low-density and low-abundance regimes, are required in order to account for the observed emission within the region. This scenario also supports the hypothesis that the optical emitting gas and the X-ray plasma are in pressure balance.

We present results of Gemini spectroscopy and Hubble Space Telescope imaging of the 3C 381 radio galaxy. Possible ionising mechanisms for the Extended Emission-Line Region were studied through state-of-the-art diagnostic analysis employing line-ratios. Photoionisation from the central engine as well as mixed-medium photoionisation models fail in reproducing both the strengths and the behaviour of the highest-excitation lines, such as [Ne v]λ3424, He ii, and [O iii]λ5007, which are measured at very large distances from the AGN. Shock-ionisation models provide a better fit to the observation. Expanding shocks with velocities higher than 500 km s −1 are capable of reaching the observed intensity ratios for lines with different ionisation states and excitation degrees. This model also provide a direct explanation of the mechanical energy input needed to explain the high-velocity line-splitting observed in the velocity field.