Simulations on Disk Galaxy Merger

By a series of simulations, including different orbital parameters, the major and minor mergers, and different coupling schemes between the spin and orbital angular momentums of stellar disks, we study the effects of prograde and retrograde encounters on the merging process of two disk galaxies. These effects include the merging timescale, orbit morphology, the stripping efficiency of galaxy's stellar and dark matter components, the variation of galaxy morphology, the formation of tidal structures, and so on. The results indicate that in the early stage of the merging process, the star stripping efficiency of retrograde encounter is significantly smaller than that of prograde encounter, hence, much smaller tidal structures will form. But it is opposite to the common belief that compared with the prograde encounter, the retrograde encounter has not obviously changed the orbit morphology and increased the merging timescale, and it has no significant effect on the stripping efficiency of stellar component. Compared with whether prograde encounter or retrograde encounter, for a minor merger, the tidal radius plays a more important role in the tidal stripping of stellar component of the satellite galaxy, the time when the tidal radius is equal to the scale length of stellar disk is the time that the stellar disk of the satellite galaxy is disrupted.