  The end state of binary-neutron-star (BNS) mergers can manifest conditions to
produce high-energy neutrinos. Inspired by the event GW170817, detected in
gravitational waves and in optical/infrared emission, we investigate a scenario
in which cosmic-ray (CR) particles are accelerated, in a population of BNS
mergers, in the energy range from the knee to the ankle. By taking into account
the measured thermal and non-thermal energy density of the photon fields in the
source environment as a function of the time after the merger, we model the CR
interactions and the consequent neutrino production. We propagate the escaped
CR and neutrino fluxes through the extragalactic space and compare the expected
diffuse fluxes to the experimental data and current limits. Depending on the
accelerated CR mass composition and on the contribution of this possible source
class to the sub-ankle CR flux, we provide indications on the rate of BNS
merger events and the amount of baryons present in the source site.
