利用星系团附近的回转半径判别宇宙学
Distinguishing cosmologies using the turn-around radius near galaxy clusters
摘要：
在星系团之外，宇宙向内的引力吸引和向外的膨胀之间的竞争导致了一个特殊的速度抵消半径，这被称为转向半径。对回转半径的测量有希望限制宇宙学参数，甚至可能限制引力的性质。然而，这样的测量是复杂的，因为星系团的周围不是球形的，而是一个复杂的细丝、薄片和空隙的集合。在本文中，我们使用数值模拟宇宙的结果来量化现实的误差条的测量的回转半径。我们发现，对于一个$Λ$ CDM宇宙学，这些误差棒通常是$20\%$的顺序。我们数值模拟了三种不同的实现暗能量模型和标量暗扇区相互作用，以解决是否可以用来约束非平凡的宇宙学的转弯半径，我们发现，只有相当极端的模型可以区分从$Λ$ CDM宇宙由于大的误差条所产生的非平凡的集群环境。
英文摘要：
Outside galaxy clusters the competition between the inwards gravitational attraction and the outwards expansion of the Universe leads to a special radius of velocity cancellation, which is called the turn-around radius. Measurements of the turn-around radius hold promises of constraining cosmological parameters, and possibly even properties of gravity. Such a measurement is, however, complicated by the fact that the surroundings of galaxy clusters are not spherical, but instead are a complicated collection of filaments, sheets and voids. In this paper we use the results of numerically simulated universes to quantify realistic error-bars of the measurement of the turn-around radius. We find that for a $Λ$CDM cosmology these error-bars are typically of the order of $20\%$. We numerically simulate three different implementations of dark energy models and of a scalar dark sector interaction to address whether the turn-around radius can be used to constrain non-trivial cosmologies, and we find that only rather extreme models can be distinguished from a $Λ$CDM universe due to the large error-bars arising from the non-trivial cluster environments.
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