Active galaxies in the local Universe: Feedback, variability, and triggering

Active galaxies in the local Universe: Feedback, variability, and triggering

This thesis investigates the coevolution of galaxies and their supermassive black holes. We use spatially resolved spectroscopic data to search for evidence of AGN feedback and triggering. Using observations from the AAT's SPIRAL instrument we show that outflows are prevalent in luminous local type 2 AGN. We use multiple component Gaussian emission line modelling to disentangle the kinematic and ionization properties of these outflows. This allows us to show that shock-like emission is present in these galaxies, demonstrating that the outflows are directly impacting the surrounding ISM within the galaxies. We show that Mrk 1018 has changed spectral type for a second time, making it one of only three `changing look' AGN to have done this. Mrk 1018 was first observed spectroscopically in 1979 and was classified as a type 1.9 AGN. Several years later Cohen et al. (1986) showed that it had gained broad emission lines and blue continuum emission leading them to reclassify it as a type 1 AGN. When we observed Mrk 1018 as part of The Close AGN Reference Survey (CARS) we noticed that the broad lines and continuum emission had dramatically decreased. We show that this recent change cannot be explained by variable obscuration along the line of sight to the AGN or temporary fuelling by a TDE. We conclude that the most likely cause is a disruption in the fuel supply to the accretion disk caused either by a wind in the BLR or a nearby massive object. Using MUSE-VLT data from CARS we search for evidence of AGN triggering by mergers or interactions. We measure the stellar kinematics of our active galaxies and a mass matched sample of inactive galaxies from CALIFA. We then measure the deviation from disk-like rotation using Kinemetry (Krajnovic et al. 2006). By comparing these two samples we show that the AGN have a slight enhancement in large-scale asymmetry.