  During their formation, emerging protoplanets tidally interact with their
natal disks. Proto-gas-giant planets, with Hills radius larger than the disk
thickness, open gaps and quench gas flow in the vicinity of their orbits. It is
usually assumed that their type II migration is coupled to the viscous
evolution of the disk. Although this hypothesis provides an explanation for the
origin of close-in planets, it also encounter predicament on the retention of
long-period orbits for most gas giant planets. Moreover, numerical simulations
indicate that planets migrations are not solely determined by the viscous
diffusion of their natal disk. Here we carry out a series of hydrodynamic
simulations combined with analytic studies to examine the transition between
different paradigms of type II migration. We find a range of planetary mass for
which gas continues to flow through a severely depleted gap so that the surface
density distribution in the disk region beyond the gap is maintained in a
quasi-steady state. The associated gap profile modifies the location of
corotation \& Lindblad resonances. In the proximity of the planet's orbit,
high-order Lindblad \& corotation torque are weakened by the gas depletion in
the gap while low-order Lindblad torques near the gap walls preserves their
magnitude. Consequently, the intrinsic surface density distribution of the disk
determines delicately both pace and direction of planets' type II migration. We
show that this effect might stall the inward migration of giant planets and
preserve them in disk regions where the surface density is steep.
