16yrs of AGNs X-ray spectral analyses from 7Ms CDF-S

Using a model of an intrinsically absorbed power-law plus reflection, with possible soft excess and narrow Fe K{alpha} line, we perform a systematic X-ray spectral analysis, both on the total 7Ms exposure and in four different periods with lengths of 2-21 months.

With this approach, we not only present the power-law slopes, column densities N_H_, observed fluxes, and absorption-corrected 2-10keV luminosities L_X_ for our sample of AGNs, but also identify significant spectral variabilities among them on timescales of years. We find that the N_H_ variabilities can be ascribed to two different types of mechanisms, either flux-driven or flux-independent. We also find that the correlation between the narrow Fe line EW and N_H_ can be well explained by the continuum suppression with increasing N_H_.