  In this talk, we discuss the physics modelling of particle spectra arising
from dark matter (DM) annihilation or decay. In the context of the indirect
searches of DM, the final state products will, in general, undergo a set of
complicated processes such as resonance decays, QED/QCD radiation,
hadronisation and hadron decays. This set of processes lead to stable particles
(photons, positrons, anti-protons, and neutrinos among others) which travel for
very long distances before reaching the detectors. The modelling of their
spectra contains some uncertainties which are often neglected in the relevant
analyses. We discuss the sources of these uncertainties and estimate their
impact on photon energy spectra for benchmark DM scenarios with $m_\chi \in
[10, 1000]\,$GeV. Instructions for how to retrieve complete tables from Zenodo
are also provided.
