Investigating the host galaxies of luminous AGN in the local universe with integral field spectroscopy
Abstract
This thesis investigates how galaxies and their super massive black holes coevolve. We use integral field spectroscopy to search for evidence of AGN feedback and triggering. We demonstrate that outflows are ubiquitous among luminous local type 2 AGN using observations from the AAT's SPIRAL instrument. Using multiple component Gaussian emission line decomposition we are able to disentangle the kinematic and ionisation properties of these winds. This allows us to argue that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies. We search for evidence of AGN triggering using data from The Close AGN Reference Survey (CARS). CARS aims to provide a detailed multi-wavelength view of 40 nearby (0.01 < z < 0.06) unobscured AGN to study the link between AGN and their host galaxies. The primary CARS observations come from the MUSE integral field unit on the VLT, and complementary multi-wavelength observations have been approved from SOFIA, Chandra, VLA, HST, and others. We compare the stellar kinematics of active galaxies from CARS to similar inactive galaxies. We then use kinemetry to estimate the degree of dynamical disturbance, to determine whether active nuclei are preferentially hosted in dynamically disturbed or merging systems. Finally, we highlight the discovery of an AGN that has changed spectral type not once, but twice. So called ‘changing look’ AGN are an uncommon phenomenon, but twice changed AGN are much rarer. This AGN first transitioned from a narrow line AGN (type 2) to a broad line AGN (type 1) in the 1980s. It was recently observed as part of CARS. Examination of the MUSE data for this particular source showed that it no longer had the spectral features typical of a type 1 AGN. The continuum emission from the accretion disk was no longer visible and the broad lines were dramatically diminished. In this talk we describe the possible reasons for this change, supported by analysis of multi-epoch optical photometry and spectroscopy, alongside data obtained through director’s discretionary time from Chandra, HST, and the VLA. We then conclude by discussing the implications of this discovery on our understanding of AGN timescales and the physics behind AGN spectral types.
- Publication:
-
American Astronomical Society Meeting Abstracts #229
- Pub Date:
- January 2017
- Bibcode:
- 2017AAS...22931903M