Lag timescale and root-mean-square of average charge as a function of density for component 0 of NGC 3783 are presented in logarithmic. Top: lag timescale calculated from Fig. 6 vs. hydrogen number density in the unit of m⁻³. The fitting results are shown as a dashed line. Bottom: root-mean square σ_C of Fe average charge vs. hydrogen number density. The intersection between σ_C = −1.0 (horizontal black line) and the fitting results (dashed line) indicate the detectable lower limit.