Distribution of the simulated Δχ² values for the EPIC-pn spectra, obtained from 10⁵ Likelihood Ratio Test (LRT) simulations in XSPEC. Left panel: simulations performed under the null model (powerlaw), comparing powerlaw versus gabs*powerlaw. Right panel: simulations performed under the null model (ThComp(diskbb)), comparing ThComp(diskbb) versus gabs*ThComp(diskbb). In both panels, the red dashed lines mark the observed Δχ² obtained from the real data when including the multiplicative Gaussian absorption component at ∼3.3 keV. The shaded histograms show the simulated Δχ² distributions under the null hypothesis, while the vertical gray dashed lines indicate the nominal 1–3σ thresholds for reference.