Measuring kinetic feedback in nearby AGN via channel maps

Abstract

We use velocity channel maps in the [O III] emission line from integral-field spectroscopy obtained with the Gemini GMOS-IFU instrument to derive the ionized gas masses, mass outflow rates, and outflow powers in the central kiloparsec of 11 nearby (z < 0.02) active galaxies. We obtain mass-outflow rates as a function of distance from the nucleus and conclude that the highest values are observed within the inner ≈ 200 pc. Using these values and the whole velocity range in the channel maps, we calculate the corresponding outflow powers, that are in the range 1037 − 1042 erg s−1. We compare the results based on channel maps with those obtained using velocity-integrated measurements and find that, for all other parameter kept fixed, the use of channel maps returns higher mass-outflow rates and kinetic powers for the outflows. Our new calculations give powers that are closer to the coupling efficiencies 0.5 ≤ f ≤ 5 per cent which is predicted by models to have a strong effect on the host galaxy, quenching star formation, with nearly half the sources above the 0.5 per cent line.