X-Ray Warm Absorber Variability of the Seyfert Galaxy Arakelian 564

We studied the variability of warm absorber clouds of ionized gas within AGN for the Seyfert 1 galaxy Arakelian 564. The X-ray spectra for four XMM-Newton observations of this object are analyzed using the EPIC and the RGS instruments. These four observations covered 11 years. The ionization parameter ξ of the absorbing matter changed between observations ( logξ = 0.889 ± 3.1 × 10 -2 for the 2000 observation and 0.437 ± 7.60 × 10 -2 for the year 2001). The X-ray soft excess is studied for the four observations using two black body parameters in EPIC spectra (the first black-body temperature is 3 0.129 ± 2.0 × 10 -2 KeV and the second is 2 1.74 ± 7.6 × 10 -2 KeV) and one black body parameter in RGS spectra.