Fitting the Fe XXVI Lyα absorption line in the fake-spectra for Athena with multiple Gaussians while the hard limit of the line width of each Gaussian component is fixed to 5 eV. The fake-spectra are computed for μ = 0.0010, assuming 100 ks observation of Athena (same as bottom right panel of Fig. 10). The total model is shown in black dashed line while the different Gaussian components are in different colors (solid lines).