广义相对论中的LRS Bianchi II型大质量弦宇宙学模型
LRS Bianchi Type-II Massive String Cosmological Models in General Relativity
摘要：
本文研究了代表大质量弦的局部旋转对称（LRS）Bianchi II型宇宙学模型。用Letelier（1983）给出的这种弦的能量-动量张量来构造大质量弦宇宙学模型，我们假定模型中的膨胀（$θ$）正比于切变（$σ$）。该条件导致$A = B^{m}$，其中A和B是度量系数，m是常数。根据m值的不同，我们导出了两类模型，即分别针对$m\neq \sqrt{2}$和$m = \sqrt{2}$的模型。对于合适的常数m（即对于$m = 1/2$），我们观察到在宇宙演化的早期阶段，在两种情况下宇宙都是由弦支配的。我们的模型是在加速阶段，这是一致的，最近的观察类型是超新星。还讨论了模型的一些物理和几何行为。
英文摘要：
The present study deals with locally rotationally symmetric (LRS) Bianchi type II cosmological models representing massive string. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive string cosmological models for which we assume that the expansion ($θ$) in the models is proportional to the shear ($σ$). This condition leads to $A = B^{m}$, where A and B are the metric coefficients and m is constant. We have derived two types of models depending on different values of m i.e. for $m\neq \sqrt{2}$ and $m = \sqrt{2}$ respectively. For suitable choice of constant m (i.e. for $m = 1/2$), it is observed that in early stage of the evolution of the universe, the universe is dominated by strings in both cases. Our models are in accelerating phase which is consistent to the recent observations of type Is supernovae. Some physical and geometric behaviour of the models are also discussed.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
