equal signal-to-noise (here S/N = 50 or 25 depending on data quality). Based on the obtained maps of the cluster we added all spectra above a fixed surface brightness where the cluster emission is homogeneously covered by all observations and obtained deep X-ray spectra for each cluster (separately for ACIS-I/-S). For a detailed description of the data reduction see .

Fitting individual spectra {#sec:ind_spec}
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![Merged X-ray spectra (ACIS-I top and ACIS-S bottom) of the cluster sample with residuals of different fitted models. Fitted `XSPEC` models: `apec+apec+zgauss` with best-fit (Bf), upper and lower confidence values (99.7 per cent) of the Gaussian flux in counts $\rm{cm^{-2}~s^{-1}}$. The annotations show the best-fit value and the confidence interval obtained using MCMC. Residuals are shown for the fit with upper (blue) and lower (red) confidence limit of the Gaussian flux. For the effective-area curve see Fig. \[fig:fakelinemerge\].[]{data-label="fig:linemerge"}](merge_limit_i_unabs.pdf "fig:"){width="48.00000%"} ![Merged X-ray spectra (ACIS-I top and ACIS-S bottom) of the cluster sample with residuals of different fitted models. Fitted `XSPEC` models: `apec+apec+zgauss` with best-fit (Bf), upper and lower confidence values (99.7 per cent) of the Gaussian flux in counts $\rm{cm^{-2}~s^{-1}}$. The annotations show the best-fit value and the confidence interval obtained using MCMC. Residuals are shown 