暗区中具有标度无关线性耦合的晚期宇宙动力学
Late universe dynamics with scale-independent linear couplings in the dark sector
摘要：
本文研究了具有能量密度分别为$ρ_A$和$ρ_B$的两个耦合暗分量的宇宙学模型的动力学。我们假设耦合的形式是$Q=Hq(ρ_A,ρ_B)$，因此两个分量的动力学结果是与尺度无关的，即不明确地依赖于哈勃标量$H$。在这个假设下，我们把注意力集中在一般的线性耦合$q=q_o+q_Aρ_A+q_Bρ_B$上，它可以被看作是由任何$q(ρ_A,ρ_B)$在晚期产生的，并且通常导致一个有效的宇宙学常数。在本文的第二部分中，我们考虑观测约束的形式耦合从超新星Ia数据，假设其中一个组件是冷暗物质。我们发现，耦合函数的常数部分是不受约束的超新星Ia数据，在典型的线性耦合函数，一个成比例的暗能量密度$ρ_{A}$是优选的强耦合制度，$|q_{A}|>1$。虽然幻影模型倾向于正耦合函数，但在非幻影模型中，不仅允许负耦合函数，而且非耦合子情况落在可能性的边界。
英文摘要：
We explore the dynamics of cosmological models with two coupled dark components with energy densities $ρ_A$ and $ρ_B$. We assume that the coupling is of the form $Q=Hq(ρ_A,ρ_B)$, so that the dynamics of the two components turns out to be scale independent, i.e. does not depend explicitly on the Hubble scalar $H$. With this assumption, we focus on the general linear coupling $q=q_o+q_Aρ_A+q_Bρ_B$, which may be seen as arising from any $q(ρ_A,ρ_B)$ at late time and leads in general to an effective cosmological constant. In the second part of the paper we consider observational constraints on the form of the coupling from SN Ia data, assuming that one of the components is cold dark matter. We find that the constant part of the coupling function is unconstrained by SN Ia data and, among typical linear coupling functions, the one proportional to the dark energy density $ρ_{A}$ is preferred in the strong coupling regime, $|q_{A}|>1$. While phantom models favor a positive coupling function, in non-phantom models, not only a negative coupling function is allowed, but the uncoupled sub-case falls at the border of the likelihood.
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