The α _vir vs. time for the G2 and G3 mergers in the (left) e2 and (right) e1 orbits viewed from a “v0” angle during the final coalescence. (Left) The red line is the mass-weighted median for α _vir from the simulation. The orange shaded region includes data within the 16th and 84th quantiles of α _vir values. The dashed lines correspond to the start of the second passage and the final coalescence of the two nuclei. The three solid lines correspond to the merger times shown in Figure 2. The horizontal dashed line indicates the median α _vir for the isolated G3 galaxy at 0.625 Gyr (Figure 1) as a baseline for comparison. The upper panel shows SFR vs. time for the second coalescence, and the right panel shows the 16th, 50th, and 84th quantiles of α _vir for PHANGS, NGC 3256, and the Antennae from the observations. In calculating α _vir, we use the U/LIRG α _CO for NGC 3256 and the Milky Way value for PHANGS and the Antennae. (Right) Same plot for G2 and G3 merger in the “e1” orbit during the final coalescence. The three solid lines correspond to three snapshots in Figure C1. The “e1” orbit has a smaller impact parameter than the “e2” orbit. We can see that the global α _vir increases dramatically right after the second passage as the SFR rises. The peak SFR also roughly corresponds with the peak α _vir, which suggests that the high α _vir might be caused by the feedback from the starburst.