  The final orbital position of growing planets is determined by their
migration speed, which is essentially set by the planetary mass. Small mass
planets migrate in type I migration, while more massive planets migrate in type
II migration, which is thought to depend mostly on the viscous evolution rate
of the disc. A planet is most vulnerable to inward migration before it reaches
type II migration and can lose a significant fraction of its semi-major axis at
this stage. We investigated the influence of different disc viscosities, the
dynamical torque and gas accretion from within the horseshoe region as
mechanisms for slowing down planet migration. Our study confirms that planets
growing in low viscosity environments migrate less, due to the earlier gap
opening and slower type II migration rate. We find that taking the gas
accretion from the horseshoe region into account allows an earlier gap opening
and this results in less inward migration of growing planets. Furthermore, this
effect increases the planetary mass compared to simulations that do not take
the effect of gas accretion from the horseshoe region. Moreover, combining the
effect of the dynamical torque with the effect of gas accretion from the
horseshoe region, significantly slows down inward migration. Taking these
effects into account could allow the formation of cold Jupiters (a > 1 au)
closer to the water ice line region compared to previous simulations that did
not take these effects into account. We thus conclude that gas accretion from
within the horseshoe region and the dynamical torque play crucial roles in
shaping planetary systems.
