High Resolution Observations of X-ray Absorbers/Emitters
  We present photoionization and collisional ionization models, and their application to three important fields: (a) the Warm Absorbers/Emitters in type 1 AGN, (b) the Warm Reflectors in Type 2 AGN, and (c) X-ray absorption of background quasars by intergalactic gas. A number of cases are investigated, and the dependences of the main parameters explored. 
F. Nicastro (1, 2, 3), M. Elvis (1), F. Fiore (2), G. Matt (4), S.   Savaglio (2) ((1) Harvard-Smithsonian Center for Astrop...