  In the light of growing evidence that blazars are responsible for part of the
astrophysical very-high-energy neutrino flux detected by IceCube, models for
neutrino production through photo-pion interactions in blazar jets have been
developed. Evidence is also mounting that photon fields originating external to
the jet are strongly favored over the co-moving primary electron synchrotron
photon field as target for photo-pion interactions. Even though those external
photon fields appear highly anisotropic in the co-moving frame of the emission
region, current models usually consider neutrino production to occur
isotropically in the co-moving frame, resulting in a beaming pattern that is
identical to intrinsically isotropic synchrotron and synchrotron self-Compton
emission. In this paper, we derive the resulting beaming patterns of neutrinos
produced by interactions wich external photon fields, taking into account all
relevant anisotropy effects. It is shown that neutrino emission resulting from
photo-pion production on a stationary and isotropic (in the AGN rest frame)
external photon field is significantly more strongly beamed along the jet
direction than intrinsically isotropic emission. For the most highly beamed
sources, this implies that expected neutrino fluxes are grossly under-estimated
or jet-power requirements for the production of a given neutrino flux grossly
over-estimated when not accounting for the proper Doppler boosting and beaming
characteristics.
