星系密度波的线性增长
The Linear Growth of the Density Wave in Galaxies
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摘要: 本文以线性密度波局部渐近解为初值,求解二维非定常流体力学方程组和泊松方程,研究星系密度波的线性增长.数值计算结果表明,线性密度波将在几千万年时间内增长到与基态同量级,形成在中心区域具有棒形结构的螺旋图样.螺旋结构的图样速度及扰动密度的增长率随空间位置及时间变化.讨论了准稳螺旋结构假设的近似性.Abstract: The aim of this article is to study the linear growth of the density wave in galaxies by means of numerically resolving unsteady, two-dimensional hydrodynamic equations coupled with Poisson equation under the condition that the local asymptotic solution of linear density wave is given.as an initial value. The results show that the perturbed peak density of linear density wave grows to the same order as the basic state density during merely tens of million years,the spiral pattern emerging which has barred structure in its inner region. The angular velocity of the spiral pattern and the growth rate of perturbed density vary gradually with changes in spatial place and time. The approximate property of quasistationary spiral structure hypothesis is discussed in this paper.
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