Abstract for Proposal 084377
Catching AGN in Deep Minimum States to Unveil Their Core Environment
The deep minimum state of AGN is characterized by a strongly suppressed or
even absent primary continuum. As the continuum disappears weak spectral
features like relativistic iron lines or narrow soft X-ray emission lines
from ionised plasmas become highly significant and their parameters can
be determined. Therefore deep minimum states offer unique possibilities
to investigate in detail the physics of the reprocessed components in AGN,
including the immediate vicinity of the supermassive black hole. Applying
our experience (several deep minimum observations) we propose 2 triggered
10ks XMM snapshot, one 80ks XMM follow-up simultaneous with one 80ks
NuSTAR one 2-orbit HST observation of an AGN in deep minimum state.
Details on Observing Strategy and Trigger Criteria
Beside a serendipitous approach (e.g. ATel) we search systematically
using two resources:
Swift Fill-in and serendipitous observations of AGNs (Grupe et
al. 2010, ApJS, 187, 64): based on previous years experience and
taking into account XMM-Newton visibility we expect to detect 1.5
low-state AGN visible per year.
XMM-Newton slews: All slew sources are public in the XMM-Newton
web-page within 1 2 weeks. We check all sources found in XMM-Newton
slews and search for AGNs which are at least 10 times fainter than
they were during ROSAT measurements.
We expect one candidate every two years. Depending on the count rate
detected by Swift or XMM-Newton slew we will decide about the (short)
XMM-Newton follow-up observation duration. If the short XMM-Newton
observation shows spectral complexity, then we plan to trigger a
further, deeper observation with an exposure time of 80
ks. Contemporaneously we want to trigger a simultaneous 80ks NuSTAR
observation and we want to trigger a 2 orbit long HST Cosmic Origins
Spectrograph (COS) observation with E130M and G160M. The reaction time
for the triggers can be some weeks depending on the visibility of the
target.