Statistical Substructure of ISP Blazar Variability: Five-Source Analysis and Class-S/Class-H Spectral Bifurcation

Five-source Swift XRT analysis of C3 ISP blazars. TXS 0506+056 (15,690 photons) and S5 0716+714 (33,064 photons) added to the three-source v6 sample. Reveals spectral bifurcation: Class-S (softening, 4/5 sources, leptonic) vs Class-H (hardening, TXS 0506+056, hadronic candidate). TXS 0506+056 shows ΔHR = +0.199, p = 0.0029, KS p = 0.0015. Detection-Limit Hypothesis quantified as N_min ∝ Fvar². Predicts neutrino-emitting blazars preferentially exhibit Class-H X-ray spectral behavior.