STATISTICAL MECHANICS OF COLLISIONLESS ORBITS. I. ORIGIN OF CENTRAL CUSPS IN DARK-MATTER HALOS
STATISTICAL MECHANICS OF COLLISIONLESS ORBITS. I. ORIGIN OF CENTRAL CUSPS IN DARK-MATTER HALOS
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DOI：
10.1088/0004-637x/722/1/851
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发表时间：
2010-10-10
影响因子：
4.9
通讯作者：
Williams, Liliya L. R.
中科院分区：
文献类型：
--
作者：
Hjorth, Jens;Williams, Liliya L. R.
本文提出了各向同性速度分布的无碰撞自引力系统的平衡统计力学理论。与现有的标准理论相比，我们引入了两个变化：（1）可能的微观状态的数量是在能量（轨道）空间，而不是相空间计算和（2）低占有数更适当地处理比他们使用斯特林的近似。结合起来，这两个修正预测，无碰撞自引力系统的松弛部分，如暗物质晕，具有与[exp（phi（0）-ψ）-1]成比例的微分能量分布N（ψ），被称为“DARKexp”。“这样的系统具有与r（-1）成比例的中心幂律密度尖点rho（r），这表明模拟暗物质晕中尖点的统计力学起源。
We present an equilibrium statistical mechanical theory of collisionless self-gravitational systems with isotropic velocity distributions. Compared with existing standard theories, we introduce two changes: (1) the number of possible microstates is computed in energy (orbit) space rather than phase space and (2) low occupation numbers are treated more appropriately than they are using Stirling's approximation. Combined, the two modifications predict that the relaxed parts of collisionless self-gravitating systems, such as dark-matter halos, have a differential energy distribution N(epsilon) proportional to [exp(phi(0)-epsilon)-1], dubbed "DARKexp." Such systems have central power-law density cusps rho(r) proportional to r(-1), which suggests a statistical mechanical origin of cusps in simulated dark-matter halos.