Probing the variability of the warm absorber in Mrk 279.

We present here the results on the detailed modeling of the complex absorption spectrum of the Seyfert 1 galaxy Mrk 279. The source was observed three times by XMM-Newton RGS for a total exposure time of 150 ks spread over three satellite orbits. The data are modeled in terms of two warm absorber (WA) components with different ionization parameters and blue-shifted with respect to the rest frame of the source. We find no significant response of the absorbing gas to the smooth (∼30%) continuum variation of the source during a two-day time scale observations. We also investigate possible long term (∼2 years) variations of the absorber, therefore putting important constraints on the distance of the absorber to the ionizing source as well as studying the possible relationships between the spectral components on long term timescales. [ABSTRACT FROM AUTHOR]