Enhanced neutrino signals from dark matter annihilation in the Sun via
  metastable mediators
  We calculate the neutrino signal resulting from annihilation of secluded dark
matter in the Sun. In this class of models, dark matter annihilates first into
metastable mediators, which subsequently decay into Standard Model particles.
If the mediators are long lived, they will propagate out from the dense solar
core before decaying. High energy neutrinos undergo absorption in the Sun. In
the standard scenario in which neutrinos are produced directly in the centre of
the Sun, absorption is relevant for E > 100 GeV, resulting in a significant
suppression of the neutrino spectrum beyond E ~ 1 TeV. In the secluded dark
matter scenario, the neutrino signal is greatly enhanced because neutrinos are
injected away from the core, at lower density. Since the solar density falls
exponentially with radius, metastable mediators have a significant effect on
the neutrino flux, even for decay lengths which are small compared to the solar
radius. Moreover, since neutrino detection cross sections grow with energy,
this enhancement of the high energy region of the neutrino spectrum would have
a large effect on overall event rates.
