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arXiv 1012.5931gr-qcmath.APmath.DG
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弱正则T2对称时空。未来发展的全球格局

Weakly regular T2 symmetric spacetimes. The global geometry of future developments

Philippe G. LeFloch, Jacques Smulevici

摘要:

在弱正则性假设下,我们发展了具有T2对称性的真空爱因斯坦时空的完全几何理论,建立了爱因斯坦场方程初值问题的整体适定性,并研究了所构造时空的整体因果结构.我们的弱正则性假设是最小的,允许在假设的对称性下给出爱因斯坦方程的意义,并解决初值问题。首先,我们引入了一个适合于对称性的框架,其中每个Christoffel符号都可以被检查为属于某个Lp空间。我们确定某些取消属性发生在表达的黎曼和里奇曲率,这使我们重新制定的初始值问题的爱因斯坦场方程时,初始数据集具有弱的规律性。其次,我们研究了弱正则初始数据集的未来发展。我们检查对称轨道的面积R必须在未来的类时方向上增长到无穷大,并且我们通过R的水平集建立了全局叶状的存在。我们的弱正则性假设只要求R是Lipschitz连续的,而描述对称轨道的初始几何的度量系数在Sobolev空间H1中,其余系数具有更弱的正则性。我们在这里开发的紧凑性参数所需的覆盖自然水平的规律性与能量的偏微分方程系统确定从爱因斯坦的场方程。

英文摘要:

Under weak regularity assumptions, only, we develop a fully geometric theory of vacuum Einstein spacetimes with T2 symmetry, establish the global well-posedness of the initial value problem for Einstein's field equations, and investigate the global causal structure of the constructed spacetimes. Our weak regularity assumptions are the minimal ones allowing to give a meaning to the Einstein equations under the assumed symmetry and to solve the initial value problem. First of all, we introduce a frame adapted to the symmetry in which each Christoffel symbol can be checked to belong to some Lp space. We identify certain cancellation properties taking place in the expression of the Riemann and Ricci curvatures, and this leads us to a reformulation of the initial value problem for the Einstein field equations when the initial data set has weak regularity. Second, we investigate the future development of a weakly regular initial data set. We check that the area R of the orbits of symmetry must grow to infinity in the future timelike directions, and we establish the existence of a global foliation by the level sets of R. Our weak regularity assumptions only require that R is Lipschitz continuous while the metric coefficients describing the initial geometry of the orbits of symmetry are in the Sobolev space H1 and the remaining coefficients have even weaker regularity. We develop here the compactness arguments required to cover the natural level of regularity associated with the energy of the system of partial differential equations determined from Einstein's field equations.

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