Results from the Monte Carlo simulations for the hypothesis of a narrow feature parameterized with an EP function with fixed curvature. First (top) panel: VHE gamma-ray spectrum from 2014 July 19 (MJD 56857.98), from Fig. 5, fitted with an LP function (thick dark gray curve), and also fitted with an LP plus an EP with β = 9.1, and centered at various energies from 0.08 TeV to 6.80 TeV in steps of 0.05 in base-10 logarithmic space (thin light gray lines). The difference in χ² values () is shown below the spectrum, using colors different from gray for cases with . Second and third panels: resulting and distributions from the 10⁴ simulated spectra. The green dashed line marks the obtained for the measured spectrum and shown in the first panel, while the blue, red, and purple solid lines depict the expected χ² distribution for 1, 2, and 3 degrees of freedom. See text in Appendix D for further details.