Speaker
Description
Photoionised gas at all scales is ubiquitously observed in AGNs, from
the optical up to the X-rays. Its density, geometry, velocity represent
a unique probe of the innermost accretion disc-scale, as well as on the
feeding and feedback connecting the AGN to the host environment.
However, current photoionisation codes usually assume time-equilibrium
and, thus, cannot self-consistently model the gas response to a
time-variable (or transient) ionising source, as for most of the AGNs,
and leads to incorrect results when fitting emission and absorption
spectra. Moreover, gas density and distance are degenerate at
equilibrium and, thus, the outflows energy and mass rates can be
determined only with order-of-magnitude uncertainties.
To gain more insights from current observations, especially in the UV
(HST) and in the X-rays (XMM-Newton, Chandra), and get ready for the
incoming XRISM X-ray telescope, we developed one of the first Time
Evolving Photo-Ionisation Device (TEPID), which follows the gas
ionisation in response to a (time-varying) luminosity source. The code
is highly flexible and can model any astrophysical scenario, from
variable AGNs to GRBs and diffuse nebulae. We are now analysing archival
XMM-Newton observations of time-variable AGN absorbers, with a
particular focus on those that will be observed in the Performance
Verification phase of XRISM.
