Rapid High Amplitude Variability in Active Galactic Nuclei

Date: 
10/10/2019 - 2:00pm to 3:00pm
Location: 
BL 339
Speaker(s) / Presenter(s): 
Dirk Grupe
I will report on the most recent discoveries by the NASA Neil Gehrels Swift mission of Active Galactic Nuclei (AGN) with high amplitude variabilities. While AGN typically vary with factors of 3 on times scales of days to years, some AGN exhibit outbursts or dramatic drops in the X-ray fluxes by factors of even more than 100. Among the most extreme cases are the Narrow-Line Seyfert 1 galaxy WPVS 007 which appears to be extremely X-ray faint, and the Seyfert 1.9 galaxy IC 3599 which has shown repeated X-ray flaring, most likely due to accretion disk instabilities. Swift capability of following objects for more than a decade with simultaneous X-ray and UV observations has allowed us to discover several of these extreme AGN.  Recent examples are IRAS 23226-3843, RX J2317-4422 and repeatedly Mkn 335 on which we triggered XMM/NuSTAR and HST observations several times in 2018 and 2019. In particular IRAS 23226-3843 is a so called changing look AGN that has changed its optical spectroscopic type several times. In most recent Swift observations IRAS 23226-3843 was found to be flaring again.
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