Abstract

Contributed Talk - Splinter AGN   (MW-1250)

In the Eye of the Storm: The Third Giant X-ray Outburst of the Extreme Changing-look AGN IC 3599

S. Wolsing, D. Grupe, S. Komossa, N. Schartel
Georg-August-Universität Göttingen, Northern Kentucky University, Max-Planck-Institut für Radioastronomie, Universidad Complutense de Madrid

The Seyfert 1.9 galaxy IC3599 is a highly variable changing look AGN. It was discovered during the ROSAT All-Sky Survey as an extremely X-ray bright AGN, but quickly faded in the following years. It was seen again in outburst in by Swift in 2010 after which we started a monthly monitoring campaign. This led to the discovery of a third giant outburst (factor > 100) in 2025 which initiated several follow-up observations with ground and space-based observatories. Optical spectroscopy revealed that the spectrum has dramatically changed displaying very strong permitted lines as well as strong coronal Fe emission lines, like they were detected after the ROSAT discovery. The most-likely explanation for these outbursts are accretion disk instabilities.