论文标题
对单型$ f（r）$ - 重力的各向异性宇宙的重建方法
A reconstruction method for anisotropic universes in unimodular $F(R)$-gravity
论文作者
论文摘要
在$ f（r）$重力的背景下，单型爱因斯坦重力的延伸用于构建一类各向异性进化方案。在单模型的GR中，公制的决定因素被限制为固定数字或函数。但是，通用各向异性宇宙的度量与单模型的约束不兼容，因此对度量的重新定义适当地考虑了约束，需要执行。单型限制是通过拉格朗日乘数在约旦框架中的$ f（r）$重力上施加的，以获取运动方程。结果方程式可以看作是一种重建方法，该方法允许确定RICCI标量的哪些功能可以实现所需的演变。为了清楚起见，调用了一些特征示例，以显示这种重建方法如何明确起作用。在单模型的$ f（r）$重力的背景下，这里考虑的de Sitter Spacetime适合描述宇宙历史的早期和后期时期。
An extension of unimodular Einsteinian gravity in the context of $F(R)$ gravities is used to construct a class of anisotropic evolution scenarios. In unimodular GR the determinant of the metric is constrained to be a fixed number or a function. However, the metric of a generic anisotropic universe is not compatible with the unimodular constraint, so that a redefinition of the metric, to properly take into account the constraint, need be performed. The unimodular constraint is imposed on $F(R)$ gravity in the Jordan frame by means of a Lagrangian multiplier, to get the equations of motion. The resulting equations can be viewed as a reconstruction method, which allows to determine what function of the Ricci scalar can realize the desired evolution. For the sake of clarity, some characteristic examples are invoked to show how this reconstruction method works explicitly. The de Sitter spacetime here considered, in the context of unimodular $F(R)$ gravity, is suitable to describe both the early- and late-time epochs of the universe history.
