Speaker
Description
The origin of Very High-Energy (VHE) gamma-ray emission in High-frequency peaked BL Lac objects (HBLs) remains debated. While standard leptonic models successfully explain the synchrotron peak, they often struggle to reproduce hard TeV spectra without extreme parameters. We explore a hybrid scenario where the VHE emission arises from the interaction of stochastically accelerated protons with a target photon field provided by shock-accelerated electrons.
We present a newly developed numerical framework designed to model these multi-messenger signatures. Our code couples a stochastic acceleration model for protons with a standard shock scenario for electrons. By implementing the analytical parameterisations of proton-photon interactions (Kelner & Aharonian 2008), we calculate the resulting photomeson cascades and secondary gamma-ray spectra. We apply this model to characteristic HBL spectral energy distributions to assess whether hadronic components can naturally account for the observed VHE hardening. Furthermore, we provide estimates for the accompanying neutrino flux, aiming to constrain the baryon loading of the jet using current limits from the IceCube Neutrino Observatory. This study offers a diagnostic tool to distinguish between leptonic and hadronic origins of blazar emission in the multi-messenger era.
