Orateur
Summary
In extragalactic jets, protons and ions become radiatively efficient at
ultrahigh energies providing a natural source of gamma rays. Hadronic
emission can readily explain puzzling features of blazars at very high energies
such as the orphan flares and the notoriously hard spectra that show
up after taking into account pair attenuation in the metagalactic radiation
field. The observed short variability time scales are challenging: they seem to
require much stronger magnetic fields than those infered from fitting leptonic
emission models to the blazar spectral energy distribution.
Simultaneous measurements of the synchrotron self-absorption turnover
and the gamma ray peak of the flaring component
could be used to resolve the ambiguities for the origin of the gamma rays.
Owing to the multi-component nature of the jet emission, high-resolution
observations are needed to pinpoint the
flaring components and to identify the relevant turnover frequencies.
