Neutrino Emission from HBLs and LBLs

The Synchrotron Proton Blazar model is a promising model to explain high energy emission from gamma-ray loud BL Lac objects like Mkn 421. In contrast to leptonic models, the hadronic explanation of gamma-ray emission predicts ultrahigh energy neutrinos. The predicted neutrino spectra from a typical High-energy cutoff BL Lac Object (HBL) and a Low-energy cutoff BL Lac Object (LBL) are presented. We find that cooling due to muon synchrotron radiation causes a cutoff of the neutrino spectrum at $\sim 10^{18}$ eV, with the exception of $\nu_\mu$ from kaon decay which may extend to higher energies if meson production takes place in the secondary resonance region of the cross section. The impact of the neutrino output from both source populations to the diffuse neutrino background is discussed.