We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q _ion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q _ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2 × 10⁴ yr before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission, morphologically suggestive of outflow, are common, their kinematic structure shows some to be in regular rotation. UGC 7342 exhibits local signatures of outflows <300 km s⁻¹, largely associated with very diffuse emission, and possibly entraining gas in one of the clouds seen in Hubble Space Telescope images. Only in the Teacup AGN do we see outflow signatures of the order of 1000 km s⁻¹. In contrast to the extended emission regions around many radio-loud AGNs, the clouds around these fading AGNs consist largely of tidal debris being externally illuminated but not displaced by AGN outflows.

Galaxies with polar rings (PRGs) are a unique class of extragalactic objects. Using these, we can investigate a wide range of problems, linked to the

We present new broad-band optical images of some merging Seyfert galaxies that were earlier considered to be non-interacting objects. In our deep images obtained at the Russian 6-m telescope we have detected elongated tidal envelopes belonging to satellites debris with a surface R-band brightness about 25–26.5 mag arcsec⁻². These structures are invisible in Sloan Digital Sky Survey (SDSS) pictures because of their photometric limit. We found that 35 per cent of the sample of isolated galaxies has undergone merging during the last 0.5–1 Gyr. Our results suggest that statistical studies based on popular imaging surveys (SDSS or Second Palomar Observatory Sky Survey (POSS-II)) can lead to underestimation of the fraction of minor mergers among galaxies with active nuclei (AGN). This fact impacts on statistics and must be taken into consideration when finding a connection between minor/major merging or interactions and nucleus activity.

The extended narrow-line region (ENLR) of an active galactic nucleus (AGN) is a region of highly ionized gas with a size of a few up to 15–20 kpc. When it shows a conical or biconical shape with the apexes pointing towards the active nucleus, this region is also called an ionization cone. Ionization cones are evidence of the unified model, which predicts an anisotropic escape of ionizing photons from a nucleus confined to a cone by a dusty torus. Many details about the complex structure of the ENLR still remain to be unveiled, such as for example the origin of the ionized gas. Here we present new results of a study of the physical and kinematic properties of the circumnuclear gas in the nearby Seyfert 2 galaxy NGC 7212. Medium- and high-resolution integral-field spectra and broad-band photometric data were collected and analysed in the frame of an observational campaign of nearby Seyfert galaxies, with the aim of handling the complicated issue of the origin of gas in the ENLR. This work is based on (i) the analysis of gas physical properties (density, temperature and metallicity), (ii) the analysis of emission-line ratios and (iii) the study of kinematics of gas and stars. By reconstructing the [O iii]/Hβ ionization map, we point out for the first time the presence of an ionization cone extended up to about 6 kpc, made of a large amount of low-metallicity gas, kinematically disturbed and decoupled from stars, a highly ionized component of which shows radial motions at multiple velocities, as proved by the complex profiles of the spectral lines. Since NGC 7212 is a strongly interacting triple galaxy system, gravitational effects are likely to be at the origin of the ENLR in this Seyfert galaxy.