Final period ratio of Jupiter and Saturn migrating in N-body simulations including the effects of a 1D gas disk. The vertical axis shows the relative surface density of the disk. The gas disk lasts 1 Myr. After the gas dissipation, the orbits of the giant planets are numerically integrated for another 50 Myr. The color code shows the MEGNO value of each system at the end of the simulation. In this set of simulations, there is no case where Jupiter and Saturn suffer close encounters (there are no black points in the figure, which is different from Figure 6).