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Rebecca McElroy (Sydney Uni)

Rebecca McElroy Colloquium: Mrk 1018 returns to the shadows after 30 years as a Seyfert 1

The Australia Telescope National Facility Colloquium
15:00-16:00 Wed 30 Nov 2016

Marsfield Lecture Theatre


We report 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 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 a wide array of sources (SOFIA, Chandra, VLA, HST, and others). 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.


Juan Madrid

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