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arXiv 1111.0946astro-ph.COgr-qchep-th
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具有宇宙学常数的弹跳模型

Bouncing models with a cosmological constant

Rodrigo Maier, Stella Pereira, Nelson Pinto-Neto, Beatriz B. Siffert

备注：
11 pages, 11 figures
发表信息：
Phys. Rev. D, 85, 023508 (2012)
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摘要：

许多作者已经提出了弹跳模型作为一种完善，甚至作为一种替代通货膨胀的描述非常早期和密集的宇宙。然而，大多数弹跳模型都包含一个来自非常大和稀薄状态的收缩阶段，在那里，暗能量可能像今天一样在加速我们的大宇宙中发挥重要作用。在这种情况下，它的存在可以改变宇宙学扰动的初始条件和演化，改变文献中已经获得的关于其振幅和频谱的已知结果。在本文中，我们假设最简单和最有吸引力的候选人的暗能量，宇宙学常数，并评估其对宇宙学扰动的演化的影响，在收缩阶段的弹跳模型，其中还包含一个标量场的潜力，允许背景解的压力和能量密度满足p = w*rho，w是一个常数。在由宇宙学常数控制的末端可以设置一个初始绝热真空态，并且对于w~0得到了几乎标度不变的扰动谱，这是弹跳模型的通常结果。然而，存在的宇宙学常数诱导振荡和运行向一个微小的红色倾斜的光谱长波长的扰动。

英文摘要：

Bouncing models have been proposed by many authors as a completion, or even as an alternative to inflation for the description of the very early and dense Universe. However, most bouncing models contain a contracting phase from a very large and rarefied state, where dark energy might have had an important role as it has today in accelerating our large Universe. In that case, its presence can modify the initial conditions and evolution of cosmological perturbations, changing the known results already obtained in the literature concerning their amplitude and spectrum. In this paper, we assume the simplest and most appealing candidate for dark energy, the cosmological constant, and evaluate its influence on the evolution of cosmological perturbations during the contracting phase of a bouncing model, which also contains a scalar field with a potential allowing background solutions with pressure and energy density satisfying p = w*rho, w being a constant. An initial adiabatic vacuum state can be set at the end of domination by the cosmological constant, and an almost scale invariant spectrum of perturbations is obtained for w~0, which is the usual result for bouncing models. However, the presence of the cosmological constant induces oscillations and a running towards a tiny red-tilted spectrum for long wavelength perturbations.

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