2026MNRAS.545f2083S

Blazars launch relativistic jets aligned with our line of sight, resulting in extreme beaming and making them among the most luminous extragalactic sources across the electromagnetic spectrum, from radio to $\gamma$-rays and potentially high-energy neutrinos. We present a comprehensive study of multimessenger emission from blazar jets powered by magnetic reconnection at varying distances from the supermassive black hole (SMBH). By generalizing previous models, we track the spatial evolution of key jet properties, including magnetization, bulk Lorentz factor, and external photon fields [accretion disc, broad-line region (BLR), dusty torus], and compute self-consistently the resulting broad-band photon spectra and neutrino emission. Our numerical simulations explore how the initial jet magnetization, particle acceleration efficiency, jet-to-accretion-power ratio, and accretion rate impact emission. We identify distinct regimes: synchrotron and synchrotron self-Compton dominate closer to the SMBH, where magnetization is high, while external Compton becomes significant near the BLR. Neutrino production is most efficient upstream of the BLR, driven by enhanced target photon densities and hard proton spectra. Our model predictions are then compared with observations of $\gamma$-ray luminosities and synchrotron peak energies of Fermi-detected blazars, highlighting magnetic reconnection as a viable mechanism for electromagnetic and neutrino emissions in astrophysical jets. Crucially, our framework assumes equal injected luminosities of pairs and protons, thereby limiting baryon loading. While our model successfully reproduces the photon emission of extreme blazars such as 3HSP J095507.9 + 355101, it cannot self-consistently account for TXS-like flares, which would require extremely high baryon loading.