Abstract We present a theoretical study of an early dark energy (EDE) model. The equation of state ω(z) evolves during the thermal history in a framework of a Friedmann-Lemaitre-Robertson-Walker Universe, following an effective parametrization that is a function of redshift z. We explore the evolution of the system from the radiation domination era to the late times, allowing the EDE model to have a non-negligible contribution at high redshift (as opposed to the cosmological constant that only plays a role once the structure is formed) with a very little input to the Big Bang Nucleosynthesis, and to do so, the equation of state mimics the radiation behaviour, but being subdominant in terms of its energy density. At late times, the equation of state of the dark energy model asymptotically tends to the fiducial value of the De Sitter domination epoch, providing an explanation for the accelerated expansion of the Universe at late times, emulating the effect of the cosmological constant. The proposed model has three free parameters, that we constrain using SNIa luminosity distances, along with the CMB shift parameter and the deceleration parameter calculated at the time of dark energy - matter equality. With full knowledge of the best fit for our model, we calculate different observables and compare these predictions with the standardΛCDM model. Besides the general consent of the community with the cosmological constant, there is no fundamental reason to choose that particular candidate as dark energy. Here, we open the opportunity to consider a more dynamical model, that also accounts for the late accelerated expansion of the Universe.

中文翻译：

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一种新颖的早期暗能量模型

摘要 我们提出了早期暗能量 (EDE) 模型的理论研究。状态方程 ω(z) 在 Friedmann-Lemaitre-Robertson-Walker Universe 框架中的热历史过程中演化，遵循作为红移 z 函数的有效参数化。我们探索了系统从辐射统治时代到后期的演变，使 EDE 模型在高红移（与宇宙常数相反，只有在结构形成后才起作用）具有不可忽略的贡献对大爆炸核合成的输入非常少，为此，状态方程模拟了辐射行为，但在其能量密度方面处于次要地位。迟到的时候，暗能量模型的状态方程渐近趋向于德西特统治时期的基准值，为宇宙后期加速膨胀提供了解释，模拟了宇宙常数的影响。所提出的模型具有三个自由参数，我们使用 SNIa 光度距离、CMB 位移参数和在暗能量 - 物质相等时计算的减速参数进行约束。在充分了解最适合我们的模型的情况下，我们计算了不同的观测值，并将这些预测与标准 ΛCDM 模型进行了比较。除了社区对宇宙常数的普遍同意外，没有任何基本理由选择那个特定的候选者作为暗能量。在这里，我们有机会考虑一个更动态的模型，