The High Energy Resolution View of Ionized Absorbers in AGN
  A number of emission and absorption features are expected to be visible in high energy resolution X-ray spectra of type 1 AGN with ionized gas along the line of sight (so called "warm absorbers"). Emission strongly depends on the geometrical configuration of the gas, while absorption along the line of sight does not. Absorption features include photoelectric absorption K and L edges along with many strong K$\alpha$, K$\beta$ and L resonance absorption lines from the most abundant elements. We present detailed simulations of our ``photoelectric + resonant absorption'' model with the high energy resolution gratings and calorimeters of AXAF, XMM and Constellation-X, and discuss the relevant physics which can be addressed with the new generation of X-ray spectrometers. 
F. Nicastro (1, 2 and 3), F. Fiore (1 and 3), G. Matt(4) ((1)   Harvard-Smithsonian Center for Astrophysics, Cambrdidge, MA ...