Modelling the Warm Absorber in NGC 3783 under pressure equilibrium conditions I. A test case for the TITAN code
Résumé
Many AGN exhibit X-ray absorption features caused by the presence of highly ionized gas located on the line-of-sight of the central continuum. Such a material is called ``Warm Absorber" (WA) and displays zones of different density, temperature and ionization. Our approach to the study of the WA relies on the assumption of pressure equilibrium, resulting in the natural stratification of the medium, which allows us to explain the presence of lines from different ionization states in many AGN observed by Chandra and XMM. Among the best WA observations available are those of NGC 3783, which we have analyzed. We have used the photoionization code TITAN, developed by our team, to calculate a grid of constant pressure models dedicated to fit the WA in NGC 3783. Our study shows that the WA can be modelled in pressure equilibrium. Finally, this work provides a good example of the application of the TITAN code to the study of the WA in AGN, and opens perspectives for its use by a larger community, through larger grids of models to be made available.