arXiv 1305.30852013-05gr-qchep-th

均匀Weysenhoff流体的Einstein-Cartan引力坍缩

Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

Amir Hadi Ziaie, Paulo Vargas Moniz, Arash Ranjbar, Hamid Reza Sepangi

备注：: 23 pages, 11 figures
发表信息：: Eur. Phys. J. C74 (2014) 3154
DOI：: 10.1140/epjc/s10052-014-3154-2

摘要：

本文研究了在负宇宙学常数下由Weysenhoff流体组成的球对称均匀物质分布的引力坍缩。我们的目的是研究扭转和自旋平均项对坍缩最终结果的影响。对于一个特定的内部时空设置，即均匀和各向同性的FLRW度规，我们得到两类解决方案的场方程依赖于自旋源参数之间的关系，$(i)$的崩溃过程最终在时空奇异性或$(ii)$它被替换为非奇异反弹。我们表明，在一定的条件下，对于一个特定的子集的前解决方案，形成的陷阱表面被阻止，从而产生的奇异性可能是赤裸裸的。在提卜勒意义上，所形成的曲率奇异性可能是强引力的。我们对后者的数值分析表明，坍缩动力学过程经历了四个阶段，其中两个发生在前反弹和其他两个反弹后的制度。我们进一步观察到，可以找到一个最小半径的视地平线曲线，这样的主要结果是，存在一个上限的坍缩体的大小，低于该上限，没有地平线形成在整个场景。

英文摘要：

We consider the gravitational collapse of a spherically symmetric homogeneous matter distribution consisting of a Weyssenhoff fluid in the presence of a negative cosmological constant. Our aim is to investigate the effects of torsion and spin averaged terms on the final outcome of the collapse. For a specific interior spacetime setup, namely the homogeneous and isotropic FLRW metric, we obtain two classes of solutions to the field equations where depending on the relation between spin source parameters, $(i)$ the collapse procedure culminates in a spacetime singularity or $(ii)$ it is replaced by a non-singular bounce. We show that, under certain conditions, for a specific subset of the former solutions, the formation of trapped surfaces is prevented and thus the resulted singularity could be naked. The curvature singularity that forms could be gravitationally strong in the sense of Tipler. Our numerical analysis for the latter solutions shows that the collapsing dynamical process experiences four phases, so that two of which occur at the pre-bounce and the other two at post-bounce regimes. We further observe that there can be found a minimum radius for the apparent horizon curve, such that the main outcome of which is that there exists an upper bound for the size of the collapsing body, below which no horizon forms throughout the whole scenario.

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