论文标题
球形双重扭曲的辐射恒星和宇宙学
Spherical doubly warped spacetimes for radiating stars and cosmology
论文作者
论文摘要
球面对称空间是恒星崩溃和不均匀宇宙学模型的环境空间。我们获得了在偶性扭曲（DW）空间上的RICCI张量的Weyl张量和协变形式的结果。在球形对称度量标准中，RICCI和电张量成为等级2，它以速度向量场及其加速度构建。它们的结构决定了DW球形指标中爱因斯坦方程中能量弹药张量的一般形式。各向异性压力和不完美的流体的热电流来自加速度的梯度和Weyl张量的电部分。为了通过热流辐射恒星塌陷，审查了带有VAIDYA指标的双重扭曲度量的连接条件，并具有径向压力的边界条件。各向同性的条件仅适应文献中的各种模型。在球形GRW太空时间（地球速度）的特殊情况下，RICCI张量的各向异性使弗里德曼方程通过电量张量偏离标准FRW宇宙学的偏差。我们介绍了“完美的2尺度”，以双向扭曲的时空中的各向异性流体来源讨论F（R）重力，并表明田间方程中的新几何术语不会改变流体能量电量张量的张量结构。
Spherically symmetric spacetimes are ambient spaces for models of stellar collapse and inhomogeneous cosmology. We obtain results for the Weyl tensor and the covariant form of the Ricci tensor on general doubly warped (DW) spacetimes. In a spherically symmetric metric, the Ricci and electric tensors become rank-2, built with a velocity vector field and its acceleration. Their structure dictates the general form of the energy-momentum tensor in the Einstein equations in DW spherical metrics. The anisotropic pressure and the heat current of an imperfect fluid descend from the gradient of the acceleration and the electric part of the Weyl tensor. For radiating stellar collapse with heat flow, the junction conditions of the doubly warped metric with the Vaidya metric are reviewed, with the boundary condition for the radial pressure. The conditions for isotropy simply accomodate various models in the literature. The anisotropy of the Ricci tensor in the special case of spherical GRW space-times (geodesic velocity), gives Friedmann equations deviating from standard FRW cosmology by terms due to the electric tensor. We introduce "perfect 2-scalars" to discuss f(R) gravity with anisotropic fluid source in a doubly warped spacetime, and show that the new geometric terms in the field equations do not change the tensor structure of the fluid energy-momentum tensor.
