Probing heavy dark matter decays with multi-messenger astrophysical data
  We set conservative constraints on decaying dark matter particles with masses
spanning a very wide range ($10^4-10^{16}$ GeV). For this we use multimessenger
observations of cosmic-ray (CR) protons/antiprotons, electrons/positrons,
neutrinos/antineutrinos and gamma rays. Focusing on decays into the $\bar{b}b$
channel, we simulate the spectra of dark matter yields by using the
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equations and the $\texttt{Pythia}$
package. We then propagate the CRs of dark matter origin till Earth by using
the state-of-the-art numerical frameworks $\texttt{CRPropa}$,
$\texttt{GALPROP}$ and $\texttt{HelMod}$ for the solution of the CR transport
equation in the extragalactic, Galactic region and the heliosphere,
respectively. Conservative limits are obtained by requiring that the predicted
dark matter spectra at Earth be less than the observed CR spectra. Overall, we
exclude dark matter lifetimes of $10^{28}$ s or shorter for all the masses
investigated in this work. The most stringent constraints reach $10^{30}$ s for
very heavy dark matter particles with masses in the range $10^{11}-10^{14}$
GeV.
