On the Implications of Late Internal Dissipation for Shallow-Decay
  Afterglow Emission and Associated High-Energy Gamma-Ray Signals
  The origin of the shallow-decay emission during early X-ray afterglows has
been an open issue since the launch of the Swift satellite. One of the
appealing models is the late internal dissipation model, where X-ray emission
during the shallow-decay phase is attributed to internal dissipation, analogous
to the prompt gamma-ray emission. We discuss possible scenarios of the late
prompt emission, such as late internal shocks, magnetic reconnection, and
photospheric dissipation. We also consider the consequences of late dissipation
and a two-component (early and late) jet model for the high-energy (GeV-TeV)
emission. We study not only synchrotron self-Compton (SSC) emission from the
early and late jets but also external inverse-Compton (EIC) emission, which is
naturally predicted in the late dissipation model. For the latter, we perform
numerical calculations taking into account the equal-arrival-time surface of
EIC photons and show that the EIC component typically has a peak at ~1-100 GeV
which may dominate over the SSC components. We demonstrate that very high
energy gamma rays from both these components are detectable for nearby and/or
energetic gamma-ray bursts, with current and future Cherenkov detectors such as
MAGIC, VERITAS, CTA and HAWC, and possibly Fermi. Although the expected event
rate would not be large, detections should be useful as a test of the model.
Multi-wavelength observations using both the ground-based telescopes and the
Swift and/or Fermi satellites are also important to constrain the models.
