Hadronic signatures from magnetically dominated baryon-loaded AGN jets

Blazars are a rare class of active galactic nuclei (AGNs) with relativistic jets pointing towards the observer. Jets are thought to be launched as Poynting-flux dominated outflows that accelerate to relativistic speeds at the expense of the available magnetic energy. In this work, we consider electron-proton jets and assume that particles are energized via magnetic reconnection in parts of the jet where the magnetization is still high (sigma >= 1). The magnetization and bulk Lorentz factor Gamma are related to the available jet energy per baryon as mu = Gamma(1 + sigma). We adopt an observationally motivated relation between Gamma and the mass accretion rate into the black hole (m) over dot, which also controls the luminosity of external radiation fields. We numerically compute the photon and neutrino jet emission as a function of mu and sigma. We find that the blazar SED is produced by synchrotron and inverse Compton radiation of accelerated electrons, while the emission of hadronic-related processes is subdominant except for the highest magnetization considered. We show that low-luminosity blazars (L-gamma less than or similar to( )10(45) erg s(-1)) are associated with less powerful, slower jets with higher magnetizations in the jet dissipation region. Their broad-band photon spectra resemble those of BL Lac objects, and the expected neutrino luminosity is L-nu+<((nu)over bar> )similar to (0.3 - 1) L-gamma. High-luminosity blazars (L-gamma >> 10(45) erg s(-1)) are associated with more powerful, faster jets with lower magnetizations. Their broad-band photon spectra resemble those of flat spectrum radio quasars, and they are expected to be dim neutrino sources with L nu+(nu) over bar << L-gamma.

Automated summary

Blazars are a rare class of active galactic nuclei with relativistic jets towards the observer. In this study, we investigate electron-proton jets energized via magnetic reconnection. The blazar spectral energy distribution (SED) is found to be dominated by synchrotron and inverse Compton radiation, while hadronic-related processes have a minor contribution. Low-luminosity blazars are associated with slower jets and higher magnetizations, resembling BL Lac objects, while high-luminosity blazars have faster jets and lower magnetizations, resembling flat spectrum radio quasars. Neutrino emission is expected to be dim in high-luminosity blazars and subdominant except for the highest magnetization considered.