(Top) The same as Figure 1 but possible synchrotron spectra are presented, which can produce the observed X-rays. Cases (a)–(c) correspond to different ordering of the key frequencies ν_a, ν_c, ν_X, and ν₂. (Bottom) The configuration of the key frequencies ν_a and ν_c. Synchrotron emission reproduces the observed X-ray luminosity only when both frequencies are located on the solid line. Above the line (gray region), the predicted luminosity exceeds the observed value, while below it the emission is insufficient.