标题： 引力不稳定性和演化更快的密度扰动 显示英文标题

标题： Gravitational instabilities and faster evolving density perturbations

摘要： 研究球对称坍缩模型中非均匀性的演化时，通过幂次展开法将爱因斯坦方程按逆径向参数展开。在线性阶段，得到了平坦、闭合和开放宇宙的密度对比度。除了通常的模式外，在无压开宇宙和闭宇宙的解中还包含无穷多个新的增长模式。在非线性阶段，我们得到了平坦宇宙的封闭形式的主要增长模式，以及开放宇宙在小时间和大时间极限下的主要增长模式。 显示英文摘要

摘要： The evolution of inhomogeneities in a spherical collapse model is studied by expanding the Einstein equation in powers of inverse radial parameter. In the linear regime, the density contrast is obtained for flat, closed and open universes. In addition to the usual modes, an infinite number of new growing modes are contained in the solutions for pressureless open and closed universes. In the nonlinear regime, we obtain the leading growing modes in closed forms for a flat universe and also, in the limits of small and large times, for an open universe.