Abstract :
High resolution X-ray spectra of AGN have been obtained for the first time due to the launch of the Chandra and XMM-Newton X-ray observatories. This paper is focussed upon the X-ray absorption properties of AGN as observed with the grating spectrometers of both satellites. It is shown that absorption line studies provide a powerful tool to study the properties of the outflowing warm winds around the active nucleus. Up to now no narrow absorption features have been identified in BL Lac objects, while Seyfert 1 galaxies show rich absorption spectra, with tens of lines from 15–20 different ions. Contrary, the first Seyfert 2 spectrum shows only emission lines, whose X-ray properties are consistent with the expected fluxes from Seyfert 1 galaxies viewed from a different angle.
