修正重力模型的观测界限
Observational Bounds on Modified Gravity Models
摘要：
修正的引力为目前观测到的宇宙加速提供了一种可能的解释。在本文中，我们研究了一般类的修正引力模型。Einstein-Hilbert作用量通过使用Ricci和Gauss-Bonnet标量的一般函数进行修改，无论是在度规形式还是在Palatini形式。我们不使用一个明确的形式的功能，但一个有效的泰勒展开到二阶的黎曼标量红移零的一般形式。这种膨胀的系数，然后重建通过宇宙膨胀的历史测量使用当前的宇宙学观测。这些是有关鬼和不稳定性的理论考虑所感兴趣的量。我们发现，目前的数据提供有趣的约束系数。下一代的暗能量调查应该会大大缩小修正引力模型的参数空间。
英文摘要：
Modified gravity provides a possible explanation for the currently observed cosmic accelaration. In this paper, we study general classes of modified gravity models. The Einstein-Hilbert action is modified by using general functions of the Ricci and the Gauss-Bonnet scalars, both in the metric and in the Palatini formalisms. We do not use an explicit form for the functions, but a general form with a valid Taylor expansion up to second order about redshift zero in the Riemann-scalars. The coefficients of this expansion are then reconstructed via the cosmic expansion history measured using current cosmological observations. These are the quantities of interest for theoretical considerations relating to ghosts and instabilities. We find that current data provide interesting constraints on the coefficients. The next-generation dark energy surveys should shrink the allowed parameter space for modifed gravity models quite dramatically.
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