부산대학교 도서관

The 1.5 Seyfert galaxy NGC 3227 has been observed by several X-ray missions. We carried out a combined analysis of the data obtained by more recent major observations of the source: two observations performed by XMM-Newton in 2000 and 2006 and six observations performed by Suzaku in 2008. A unified model, which is consistent with all eight observations by the two satellites with large intensity and spectral changes, was constructed. The model consists of a hard power law withe the spectral index of Gamma Hard = 1.4-1.7, which is interpreted as the Comptonized emission from the corona above an accretion disk. In the high-flux states, an additional soft excess component dominates, which is consistent with a model with either a steeper power law with Gamma Soft = 3.3-3.85, or the warm Comptonization component. These emissions from the central engine are absorbed by a partial covering material and warm absorbers. A reflection component and several emission lines are also present. We examined the relationship between the intrinsic luminosity and the absorbers' physical parameters such as the column density, which suggests that the source expanded significantly during the bright states when the soft excess is greatly enhanced.
Comment: 16 pages, 6 tables, and 10 figures