从球形坍缩实验得出的系统平衡形态
On the equilibrium morphology of systems drawn from spherical collapse experiments
摘要：
我们提出了一个纯粹的理论研究的形态演变的自引力系统形成的N点源的无耗散崩溃。我们探讨的质量和长度的分辨率的影响，形成的三轴结构的增长由不稳定性引发的过量的径向轨道。我们指出，随着分辨率的增加，平衡的转变，从轻度扁长，扁圆。轴向纵横比的收敛需要N ~= 100000或更大的粒子数。软化的上限，e ~ 1/256，也被确定。然后，我们研究了由无标度冷态初始质量分布ro ~ r^-g（0 <= g <= 2）形成的一组平衡态的性质。对于最初更多的峰值结构（g的较大值），扁圆度增强。我们绘制了空间密度分布图，发现当g <= 3/2，质量分数<~ 0.1%时，没有证据表明存在幂律内部结构。然而，当3/2 < g <= 2时，平衡态的质量分布与指数~g的幂律很好地匹配，直到质量分数~ 10%.We解释这是因为当中心发生更多的相混合时，对于更多的峰值分布，有效的剧烈弛豫。我们映射出的平衡的速度场，并注意到，在小半径的速度粗粒度分布函数（DF）是麦克斯韦的一个非常好的近似。
英文摘要：
We present a purely theoretical study of the morphological evolution of self-gravitating systems formed through the dissipationless collapse of N-point sources. We explore the effects of resolution in mass and length on the growth of triaxial structures formed by an instability triggered by an excess of radial orbits. We point out that as resolution increases, the equilibria shift, from mildly prolate, to oblate. A number of particles N ~= 100000 or larger is required for convergence of axial aspect ratios. An upper bound for the softening, e ~ 1/256, is also identified. We then study the properties of a set of equilibria formed from scale-free cold initial mass distributions, ro ~ r^-g with 0 <= g <= 2. Oblateness is enhanced for initially more peaked structures (larger values of g). We map the run of density in space and find no evidence for a power-law inner structure when g <= 3/2 down to a mass fraction <~0.1 per cent of the total. However, when 3/2 < g <= 2, the mass profile in equilibrium is well matched by a power law of index ~g out to a mass fraction ~ 10 per cent. We interpret this in terms of less-effective violent relaxation for more peaked profiles when more phase mixing takes place at the centre. We map out the velocity field of the equilibria and note that at small radii the velocity coarse-grained distribution function (DF) is Maxwellian to a very good approximation.
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