Upper panel: Chandra/ACIS spectra extracted from the circular region shown in Fig. 1 for all observations performed between 2016 and 2021 (see Table A.1), with the corresponding best-fit model and residuals. Dotted lines show each component of the best fit model for each epochs. Lower panel: combined spectrum obtained by summing all the observations shown in the upper panel. The ⁴⁴Sc line is modelled by a narrow Gaussian at 4.076 keV. Dotted lines indicate the different components of the best-fit model.