论文标题
通过苛性边界识别暗物质光环
Identifying Dark Matter Haloes by the Caustic Boundary
论文作者
论文摘要
暗物质密度在苛性表面的位置形式上是无限的，那里的暗物质纸在相空间中折叠。苛性碱分开具有不同数量流的多流域。通过苛性阶段时，体积元素通过向外旋转来改变奇偶校验。作为测量零结构，通过物质密度场对苛性碱的识别通常仅限于细粒度模拟。取而代之的是，可以使用Lagrangian Sub-manifold X（Q，T）的三角剖分直接使用通用的纯几何算法来直接识别苛性算法，其中x和q是eulerian和lagrangian坐标。一组三角形是模拟中的粒子，苛性表面近似。已经证明，通过建立最大的凸腐蚀性，找到暗物质光环是非常可行的。不需要关于边界几何形状或临时参数的更具体的假设。我们理想化但无疑的通用模拟中的光环边界既不是球形的也不是椭圆形，而是不对称的。对单个颗粒的动能和势能的分析以及整个晕圈的分析以及对二维相空间的检查表明，光环在重力上是绑定的。
Dark matter density is formally infinite at the location of caustic surfaces, where dark matter sheet folds in phase space. The caustics separate multi-stream regions with different number of streams. Volume elements change the parity by turning inside out when passing through the caustic stage. Being measure-zero structures, identification of caustics via matter density fields is usually restricted to fine-grained simulations. Instead a generic purely geometric algorithm can be employed to identify caustics directly by using triangulation of Lagrangian sub-manifold x(q, t) where x and q are Eulerian and Lagrangian coordinates obtained in N-body simulations. The caustic surfaces are approximated by a set of triangles with vertices being the particles in the simulation. It is demonstrated that finding a dark matter halo is quite feasible by building its owtermost convex caustic. Neither more specific assumptions about the geometry of the boundary nor ad hoc parameters are needed. The halo boundary in our idealized but undoubtably generic simulation is neither spherical nor ellipsoidal but rather remarkably asymmetrical. The analysis of the kinetic and potential energies of individual particles and the halo as a whole along with an examination of the two-dimensional phase space has shown that the halo is gravitationally bound.
