标题： 膜各向同化在额外维Tolman-Bondi宇宙中 显示英文标题

标题： Brane Isotropisation in Extra-Dimensional Tolman-Bondi Universe

摘要： 我们考虑一个3-膜在额外维的Tolman-Bondi宇宙中的动力学，其中空间的原点起着特殊的作用。嵌入方式的选择使得膜上的诱导物质分布尊重额外维空间中物质的球对称性。研究了探测膜上的幻影宇宙学，结果得到一个非均匀和各向异性的四维宇宙学，其中空间的原点也是特殊的。我们随后关注原点周围的时空几何，并表明初始上不均匀和各向异性的诱导几何会收敛到一个各向同性和均匀的弗里德曼-勒梅特四维时空。例如，当一个3-膜嵌入到一个五维物质主导模型中时，原点周围的四维动力学会收敛到一个辐射主导时期的弗里德曼-勒梅特宇宙。我们分析了这个各向同化过程，并表明它是一个晚期时间吸引子。 显示英文摘要

摘要： We consider the dynamics of a 3-brane embedded in an extra-dimensional Tolman-Bondi Universe where the origin of space plays a special role. The embedding is chosen such that the induced matter distribution on the brane respects the spherical symmetry of matter in the extra dimensional space. The mirage cosmology on the probe brane is studied, resulting in an inhomogeneous and anisotropic four dimensional cosmology where the origin of space is also special. We then focus on the spatial geometry around the origin and show that the induced geometry, which is initially inhomogeneous and anisotropic, converges to an isotropic and homogeneous Friedmann-Lemaitre 4d space-time. For instance, when a 3-brane is embedded in a 5d matter dominated model, the 4d dynamics around the origin converge to a Friedmann-Lemaitre Universe in a radiation dominated epoch. We analyse this isotropisation process and show that it is a late time attractor.