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arXiv 1507.01535astro-ph.COgr-qc
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这是一个非常黑暗的世界:超越简单指数势的相互作用的$ϕ$ CDM模型的背景演变

It's a dark, dark world: Background evolution of interacting $ϕ$CDM models beyond simple exponential potentials

Suprit Singh, Parminder Singh

摘要:

我们研究了背景宇宙动力学与三个组成部分的源内容:辐射流体,正压流体模仿的物质部门和一个单一的标量场,它可以作为暗能量引起的后期加速阶段。使用众所周知的无量纲变量,我们铸造的动力学方程成一个自治系统的常微分方程(ASODE),这是研究通过计算不动点和条件,其稳定性。首先将物质流场和标量场解耦,然后考虑二者之间的耦合形式为$Q = \sqrt{2/3}κβρ_m\dotϕ$,其中$Q = \sqrt{2/3}κβρ_m\dotϕ$为正压流体密度。我们分析的重点是,对于ASODE的封闭性,我们只要求加加速度$Γ= V V"/V'^2$是加速度的函数$z = - M_p V'/ V$,即$Γ= 1+ f(z)$。通过这种方式,我们能够容纳超过简单指数势的一大类势。分析是完全通用的和\emph{independent}的形式的潜在的标量场。作为分析的一个例证和证实,我们考虑$μ/z^2$,$μ/z$,$(μ-z)/z^2$和$(μ-z)$形式的$f(z)$数值计算宇宙学参数的演化与无耦合。的方法和结果的影响进行了讨论。

英文摘要:

We study the background cosmological dynamics with a three component source content: a radiation fluid, a barotropic fluid to mimic the matter sector and a single scalar field which can act as dark energy giving rise to the late-time accelerated phase. Using the well-known dimensionless variables, we cast the dynamical equations into an autonomous system of ordinary differential equations (ASODE), which are studied by computing the fixed points and the conditions for their stability. The matter fluid and the scalar field are taken to be uncoupled at first and later, we consider a coupling between the two of the form $Q = \sqrt{2/3}κβρ_m\dotϕ$ where $ρ_m$ is the barotropic fluid density. The key point of our analysis is that for the closure of ASODE, we only demand that the jerk, $Γ= V V"/V'^2$ is a function of acceleration, $z = - M_p V'/ V$, that is, $Γ= 1+ f(z)$. In this way, we are able to accommodate a large class of potentials that goes beyond the simple exponential potentials. The analysis is completely generic and \emph{independent} of the form of the potential for the scalar field. As an illustration and confirmation of the analysis, we consider $f(z)$ of the forms $μ/z^2$, $μ/z$, $(μ-z)/z^2$ and $(μ-z)$ to numerically compute the evolution of cosmological parameters with and without coupling. Implications of the approach and the results are 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。

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