We have analyzed the data sets of two long observation of the
Seyfert 1 galaxy MCG-6-30-15 performed with ASCA and Suzaku, in 1999 and
2006, respectively. We confirmed that the Root Mean Square (RMS)
variability in 1999 indicates a significant decrease in the disk-line
energy band(5.0---6.6 keV) more rapidly than those in the other energy
bands, as time-bin-width increases from $10^{4}$ sec to $10^{5}$ sec,
as already reported by Matsumoto et al. (2003). On the other hand, RMS
variability in 2006 does not show such a rapid decrease
in the disk-line energy band, which is explained with a simple
two-component
model such that normalization of the power-law component is variable and
the disc reflection component is constant. On the other hand, the
energy dependent variability in 1999 cannot be explained by this model,
but is required to introduce a variable warm absorber with the typical
variation time scale longer than that of the continuum(Inoue and
Matsumoto 2003).
In this talk, we apply the warm absorber model by Inoue and Matsumoto
(2003) to the 2006 data, and examine if the MCG-6-30-15 RMS spectra
could be explained without introducing the disk line model. |