Binary Black Holes and Gravitational Radiation

* 9800970拉古纳描述黑洞及其运动是过去五年中数值相对论激烈活动背后的主要推动力。 大量的工具已经从这个追求，特别是那些产生的二元黑洞合作开发。 然而，尽管计算机技术、数值算法和对爱因斯坦场方程的理解取得了进步，但对最后几个轨道和黑洞双星系统合并的模拟尚未实现。 宾夕法尼亚州立大学的小组的主要目标将是与匹兹堡、得克萨斯州和波茨坦的小组密切合作，继续开发并将这个黑洞碰撞之谜中缺失的组件整合到碰撞和辐射问题的完整解决方案中。 宾夕法尼亚州立大学的工作将主要集中在两个密切相关的领域：i）视视界边界条件和ii）应用于包含移动黑洞的时空的3+1演化的规范或坐标条件。 移动的黑洞，3+1演化迄今已进行利用等距条件，迎头碰撞的情况下，或分析的失误和移位条件，助推单黑洞系统。 一个完整的表观视界边界条件切除移动黑洞奇点尚未完全实现。 类似地，到目前为止，很少有研究完全解决了为3D演化构建规范条件的问题，这些规范条件控制场变量的无约束非物理增长，也称为网格拉伸。 为了研究黑洞演化的这两个基本方面，将考虑以下三个问题：i）助推的单黑洞，ii）黑洞的散射和iii）单轨道和合并的双系统。 这些问题建立在复杂性之上（移动的单个视视界、引力辐射、多个视视界、共转网格等）;因此，它们提供了一个自然的一步一步的路径来挑选和解决黑洞演化的特定方面，直接关系到一般的螺旋黑洞合并的最终目标。 黑洞的散射和双星系统的轨道或合并的模拟将产生关于引力辐射和相互作用奇点的性质的有价值的信息。 此外，这一努力的相关性不仅限于与黑洞碰撞模拟有关的基本含义;同样重要的是以前研究和合作模型的连续性，以及使用二元黑洞联盟开发的基础设施。 特别是，合作将发挥关键作用，因为目前的工作将不直接考虑外部边界条件、初始数据和并行化等重要领域的工作。

***9800970LagunaDescribing black holes and their motion has been the main thrust behind the intense activity in Numerical Relativity during the last half decade. A large number of tools have been developed from this quest, in particular those arising from the Binary Black Holes collaboration. However, in spite of the advancements in computer technology, numerical algorithms and understanding of Einstein's field equations, simulations of the last few orbits and the coalescence of black hole binary systems have not yet been achieved. The primary objective of the group at Penn State will be to continue developing, and integrating into a complete solution to the collision and radiation problem, the missing components of this Black Hole Collision Puzzle, in close collaboration with the groups at Pittsburgh, Texas and Potsdam. The effort at Penn State will mainly focus on two closely related areas: i) apparent horizon boundary conditions and ii) gauge or coordinate conditions applied to 3+1 evolutions of spacetimes containing moving black holes. Moving black hole, 3+1 evolutions have so far been performed taking advantage of isometry conditions, for the case of head-on collisions, or analytic lapse and shift conditions, for boosted single black holes systems. A complete apparent horizon boundary condition to excise moving black hole singularities has not yet been fully implemented. Similarly, up to this point, few studies have completely addressed the issue of constructing gauge conditions for 3D evolutions which control unbound unphysical growth of field variables, also known as grid stretching. To investigate these two fundamental aspects of black hole evolutions, the following three problems will be considered: i) boosted single black holes, ii) scattering of black holes and iii) single orbit and merger of binary systems. These problems build upon complexity (moving single apparent horizon, gravitational radiation, multiple apparent horizons, corotating meshes, etc.); thus, they provide a natural step-by-step path to single out and solve specific aspects of black hole evolutions, directly relevant to the ultimate goal of generic inspiral black hole coalescences.Successful solutions to these problems will represent progress beyond that exclusively in the computational front. Scattering of black holes and simulations of an orbit or coalescence of binary systems will yield valuable information regarding gravitational radiation and the nature of interacting singularities. Furthermore, the relevance of this effort extends to more than its fundamental implications in connection with black hole collision simulations; equally important will be the continuity of previous studies and collaborative models, as well as the use of infrastructure developed by the Binary Black Holes Alliance. Collaborations, in particular, will play a crucial role since work on important areas such as outer boundary conditions, initial data and parallelization will not be directly considered by the present effort.***