Upper panel: Average 0.3−10 keV spectrum of J1431 (black points). Only the EPIC-pn is shown for clarity, fitted with an absorbed power law (solid blue line) and a composite model (solid black line) consisting of an absorbed power law and a thermal blackbody (dotted black lines) with parameters reported in the text. Lower panel: Residuals of the two fits are shown with blue and black points, respectively.