  The gamma-ray halo around Geminga is formed owing to the slow diffusion of
the electrons released by the Geminga PWN. The latest HAWC and HESS
observations exhibit complex features in the TeV gamma-ray spectrum of the
Geminga halo. We first show that the new results cannot be interpreted by the
commonly used simple model, where a single power-law injection spectrum and an
energy index of $\delta=1/3$ for the diffusion coefficient are assumed. We then
propose a two-population electron injection model based on the x-ray
observations of the Geminga PWN, which consists of a population of freshly
accelerated electrons escaping from the PWN through rapid outflows and a
population trapped longer inside the PWN before escaping. The two-population
model interprets the HAWC and HESS data well, and the goodness of fit improves
significantly compared with the single power-law injection model. It also
predicts a different energy dependency of the gamma-ray profile from the single
power-law model, which could be tested by LHAASO in the coming future. We note
that a $\delta$ slightly larger than 1 is needed to fit the HAWC and HESS data
consistently. We also discuss the possible improvements by adopting the
two-zone diffusion model.
