Spectrum of black-body emission from warm (left panel) and cold (right panel) disc. The dot-dashed black line shows the SED 30.4 days prior to merger for both simulations. The straight grey line shows the total SED right before merger. The blue dashed, purple dot-dashed, and pink dotted lines show the contribution from different regions of the disc 0.03 days before merger. The dashed blue line shows the contribution of the disc inside r = a, which is absent in the pre-merger spectra, while it contributes significantly to the X-ray flux of the initial (i.e. t = 30.4 days) warm disc spectrum. The purple dot-dashed line shows the contribution from the gas at radii a < r < 3a, while the dotted pink line shows the circumbinary disc contribution.