Speaker
Description
AGN accretion is likely episodic over timescales of 10^(5-6) years,
and the community is still exploring the full range of diversity in
accretion flow behaviors. We are attempting to distinguish between
major changes in accretion rate either on "global" scales (global
supply of gas turned on/off) versus on "local" scales (events
originating within the disk/corona). We are also keen to examine how
all accretion flow components react and interact during such major
changes in accretion.
The eROSITA X-ray telescope aboard Spectrum X/Gamma performed multiple
all-sky X-ray surveys, including monitoring a vast sample of AGN and
galaxies. We identified candidate extragalactic transient X-ray
ignition/shutdown events, associated with extremes of accretion onto
supermassive black holes, For selected events, we triggered
multi-year, multi-wavelength follow-up monitoring programs to track
how the X-ray corona, accretion disk, and BLR responded the major
changes in accretion rate.
We present an update for campaigns on selected candidate
X-ray-selected transients, and what new insights have been gained.
Selected events include flaring transients in persistently- accreting
AGN, likely driven by instabilities originating in their disks, a BLR
ionization response to a temporary X-ray coronal flux dimming, and a
long-term X-ray dimming likely due to a clumpy, dust-free disk wind.
