  The interactions of ultra-high-energy cosmic rays (UHECRs) in extragalactic
space with photons of the cosmic microwave background (CMB) and extragalactic
background light (EBL) can generate high-energy neutrinos and photons.
Simulations of UHECR propagation require knowledge about physical quantities
such as the spectrum of the EBL and photodisintegration cross sections. These
assumptions, as well as the approximations used in the codes, may influence the
computed UHECR spectrum and composition, and the associated cosmogenic neutrino
and photon fluxes. Following up on our previous work where we studied the
effects of these uncertainties on the UHECR spectrum and composition, here we
quantify those on neutrino fluxes and production rates of photons, electrons,
and positrons, using the Monte Carlo codes CRPropa and SimProp, in various
astrophysical scenarios. We show that cosmogenic neutrinos are more sensitive
to the choice of EBL model than UHECRs, whereas the overall cosmogenic
gamma-ray production rates are relatively independent of propagation details.
We also find significant differences between neutrino fluxes predicted by the
latest released versions of CRPropa and SimProp, and discuss their causes and
possible improvements in future versions of the codes.
