星际介质在星系形成数值模拟中的作用(英文)

Numerical Simulations of the Interstellar Medium during Galaxy Formation

通过对一百多个星系形成数值模拟和试验的分析,现在可以对引力的树结构算法和平滑粒子流体力学(Smoothed Particle Hydrodynamics,SPH)这两种数值模拟技术的准确性和可靠性做定量的估计。这些结果表明若给SPH方法中使用的平滑半径(h)固定一个下限值,可能会导致数值解的准确性严重下降。若随时调整h的值使得SPH方法计算粒子的邻近粒子数总和保持不变,则可以避免这种有害的影响,使准确性得到提高。结果还表明为了可以准确地模拟原星系的坍缩,小心地选取那些影响引力加速度准确性的参量尤其重要。

The accuracy and reliability of the Treecode gravity and Smoothed Particle Hydrodynamics （SPH） techniques were quantified in more than 100 galaxy formation simulations and tests. It was found that if a lower limit on the value of the SPH smoothing radius h is imposed, a commonly used approach, the accuracy of solutions may be severely degraded. However if h is allowed to evolve freely to maintain a constant number of neighbours in SPH summations, such unwanted effects can be avoided and accuracy improved. The parameters which control the accuracy of gravitational accelerations in particular must be chosen carefully, if a proto-galactic collapse is to be modelled reliably.