The observations of gamma-ray bursts ( GRBs ) such as 980425 , 031203 and 060218 , with luminosities much lower than those of other classic bursts , lead to the definition of a new class of GRBs – low-luminosity GRBs .
The nature of the outflow responsible for them is not clear yet .
Two scenarios have been suggested : one is the conventional relativistic outflow with initial Lorentz factor of order of \Gamma _ { 0 } \gtrsim 10 and the other is a trans-relativistic outflow with \Gamma _ { 0 } \simeq 1 - 2 .
Here we compare the high energy gamma-ray afterglow emission from these two different models , taking into account both synchrotron self inverse-Compton scattering ( SSC ) and the external inverse-Compton scattering due to photons from the cooling supernova or hypernova envelope ( SNIC ) .
We find that the conventional relativistic outflow model predicts a relatively high gamma-ray flux from SSC at early times ( < 10 ^ { 4 } { s } for typical parameters ) with a rapidly decaying light curve , while in the trans-relativistic outflow model , one would expect a much flatter light curve of high-energy gamma-ray emission at early times , which could be dominated by both the SSC emission and SNIC emission , depending on the properties of the underlying supernova and the shock parameter \epsilon _ { e } and \epsilon _ { B } .
The Fermi Gamma-ray Space Telescope should be able to distinguish between the two models in the future .