Unfolded energy spectra of SXP31.0. The spectra were spaced along the y-axis for visual convenience with the factors shown. The black, green, magenta, blue, and red points correspond to the epoch 1–5 data and their respective model approximations. The dashed lines represent the individual model components (cutoffpl, bbodyrad, gauss, and a second bbodyrad) for the epoch 5 dataset. Panels (b), (c), and (d) show the residuals of the epoch 1 dataset when fitted with the cutoffpl model alone, with an additional bbodyrad component, and with two bbodyrad components, respectively.