  We perform a combined likelihood analysis for the IceCube 6-year high-energy
starting events (HESE) and 8-year throughgoing muon events above 10 TeV using a
two-component neutrino flux model. The two-component flux can be motivated
either from purely astrophysical sources or due to a beyond Standard Model
contribution, such as decaying heavy dark matter. We find that the
astrophysical plus dark matter interpretation is mildly preferred by the
current data over the purely astrophysical explanation. As for the
astrophysical neutrinos, we consider two different source flavor compositions
corresponding to the standard pion decay and muon-damped pion decay sources. We
find that the latter is slightly preferred over the former as the high-energy
component, while the low-energy component does not show any such preference. We
also take into account the multi-messenger gamma-ray constraints and find that
our two-component fit is compatible with these constraints, whereas the
single-component power-law bestfit to the HESE data is ruled out. The
astrophysical plus dark matter interpretation of the two-component flux is
found to be mildly preferred by the current data and the gamma-ray constraints
over the purely astrophysical explanation.
