星系间引力相互作用过程中盘状星系结构的演化

盘状星系的形成和演化是天文学研究的重要前沿课题。在星系形成理论中，随红移的增加，星系间的引力相互作用（包括碰撞、并合及近距离交会）更加频繁，驱使星系结构发生改变，其恒星运动学和动力学特征量也随之演化。另外，观测发现盘状星系随红移增加而更团块化，该团块化星系被认为是盘状星系的前身，它们如何通过与邻近星系的碰撞演化为低红移处的盘状星系，需要仔细研究。棒旋星系是盘状星系的一个重要类型，研究其棒状结构的形成与演化机制，也是重要问题。本项目将采用多体粒子数值计算的方法，研究高红移处团块化星系与其伴星系碰撞后的结构和动力学演化，进而研究低红移处盘状星系与其它星系相互作用后，其棒状结构的演化及恒星的动力学。在此基础上，把研究范围扩展到宇宙学尺度，基于最新的大型数值模拟Illustris得到的盘状星系，定量分析团块及棒状结构在碰撞与并合过程中的演化及内部恒星动力学，揭示这些结构形成的主导机制。

The formation and evolution of disk galaxy is among the most widely studied subjects in astronomy. According to the theory of galaxies formation, the gravitational interactions of galaxies, including collisions, mergers and encounters of galaxies, take place more frequently at higher redshift. The structure, kinematics and dynamics of the galaxies are altered due to such interactions. There are indications that, the disk galaxies become clumpier at higher redshift. Those clumpy galaxies are the progenitors of disk galaxies at the present-day. It is interesting to study how clumpy galaxies evolve to the present-day disk galaxies undergoing the collisions from nearby galaxies. On the other hand, barred galaxy is an important, Hubble-type disk galaxy. It is necessary to study the formation and evolution of the bar structures in a disk galaxy. In this proposal, we will use N-body simulations to investigate the structure, the dynamics, and the evolution of clumpy galaxies undergoing collisions from their nearby galaxies at high redshift. Furthermore, the evolution of bars and the dynamics of disk galaxies at lower redshift will also be studied after taking into account the interactions with nearby galaxies. Moreover, we will consider the simulated disk galaxies obtained from Illustris, one of the latest cosmological simulations. The evolution of clumpy structures and the bar structures of disk galaxies will be investigated, and the kinematics and dynamics of galaxies will be quantitatively analyzed. An important goal is to figure out what mechanism is responsible for the formation of these structures.