three models compared to the *pow* one, which is a ‘positive’ result[^11]. When comparing the *comptt* to the *diskbb* and *pow\*highe* models we obtain BIC numbers between 0 and 2, which indicate that the *comptt* is ‘preferred’ over these models.

To quantify the significance of the spectral cut-off, we also try to fit a broken power-law with the two slopes tied together and then thaw one of them and use the F-test to compare the fits. The F-test assesses whether the improvement of the $\chi^{2}$ is due to chance or to the new component being significant (e.g., @1989sgtu.book.....B). We obtain a break energy of 4.7$^{+0.6}_{-0.9}$ keV, an F-statistic value of 6.04, and a probability of 0.006, which is $<<$1 and thus indicates that the cut-off is significantly there.

[lccccccccc]{} Model & $N_\mathrm{H}$ & $\Gamma/T_\mathrm{in}$ & Cut-off & $T_\mathrm{0}$ & $kT_\mathrm{e}$ & $\tau$ & Norm. & Flux & $\chi^{2}$/dof\
& (10$^{22}$ cm$^{-2}$) & ( /keV) & (keV) & (keV) & (keV) & & &(erg cm$^{-2}$ s$^{-1}$) &\
*pow* & 0.05$^{+0.06}_{-0.05}$ & 1.3$^{+0.2}_{-0.2}$ & – & – & – & – &(3.4$^{+0.8}_{-0.6}$) $\times$ 10$^{-5}$ & 3.7$^{+0.4}_{-0.3}$ $\times$ 10$^{-13}$ & 51.06/34\
*pow\*highe* & 0.02$^{+0.03}_{-0.02}$ & 0.9$^{+0.2}_{-0.3}$ & 3$^{+2}_{-1}$ & – & – & 