Fitting the Fe XXV (left) and Fe XXVI (right) absorption line in the fake-spectra (red, plus symbols) of XRISM (top) and Athena (bottom) with multiple Gaussians components. The fake-spectra correspond to 100 ks observations along i = 21° through the MHD model with μ = 0.0010. Each fit also shows the constituent Gaussian components. The total model is shown in black dashed line. The higher photon counts indicates Athena’s higher effective area. The shape of the line profile is captured more accurately by Athena because of higher energy resolution. The ratio of data/model is shown at the bottom of each fit.