IXPE spectra. Top panel: IXPE total background-subtracted Stokes I(E) spectrum in the 3−6 keV band from the IXPE region (see Figs. 2 and 3) is shown with the black points. The red line in the top panel shows Chandra’s Wings-e region model (see Fig. 4) convolved with the IXPE response. Bottom panel: Stokes Q(E) and U(E) spectra of the IXPE region: red and blue points, respectively. The solid lines show the expected spectra for Chandra’s Wings-e model and the best-fitting polarization degree PD = 57 ± 18% and angle PA = 21 ± 9°.