Study of background scaling in the ²⁶Al region. Bottom panel: AIC, similar to Fig. 5a, but as a function of energy. From the optimal AIC at each energy bin, the flux is determined (black data points, upper panel, left axis). In addition, we show the fitted background (grey), divided into continuum (blue) and line (green) contributions (upper panel, right axis). To the black data points, a degraded Gaussian line on top of a power-law continuum is fitted, and shown as 1, 2, and 3σ uncertainty bands. The dotted line marks the zero flux level.