Dark energy could play a role at redshifts $z\gg \mathcal{O}(1)$. Many quintessence models possess scaling or attractor solutions where the fraction of dark energy follows the dominant component in previous epochs of the Universe’s expansion, or phase transitions may happen close to the time of matter-radiation equality. A non-negligible early dark energy (EDE) fraction around matter-radiation equality could contribute to alleviate the well-known $H_0$ tension. In this work, we constrain the fraction of EDE using two approaches: first, we use a fluid parametrization that mimics the plateaux of the dominant components in the past. An alternative tomographic approach constrains the EDE density in binned redshift intervals. The latter allows us to reconstruct the evolution of ${\mathrm{\Omega }}_{\mathrm{de}}(z)$ before and after the decoupling of the cosmic microwave background (CMB) photons. We have employed Planck data 2018, the Pantheon compilation of supernovae of Type Ia (SNIa), data on galaxy clustering, the prior on the absolute magnitude of SNIa by SH0ES, and weak lensing data from $\mathrm{KiDS}+\mathrm{VIKING}\text{−}450$ and DES-Y1. When we use a minimal parametrization mimicking the background plateaux, EDE has only a small impact on current cosmological tensions. We show how the constraints on the EDE fraction weaken considerably when its sound speed is allowed to vary. By means of our binned analysis we put very tight constraints on the EDE fraction around the CMB decoupling time, $\lesssim 0.4\%$ at $2\sigma$ c.l. We confirm previous results that a significant EDE fraction in the radiation-dominated epoch loosens the $H_0$ tension, but tends to worsen the tension for ${\sigma }_8$. A subsequent presence of EDE in the matter-dominated era helps to alleviate this issue. When both the SH0ES prior and weak lensing data are considered in the fitting analysis in combination with data from CMB, SNIa and baryon acoustic oscillations, the EDE fractions are constrained to be $\lesssim 2.6\%$ in the radiation-dominated epoch and $\lesssim 1.5\%$ in the redshift range $z\in (100,1000)$ at $2\sigma$ c.l. The two tensions remain with a statistical significance of $\sim 2–3\sigma$ c.l.

中文翻译：

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重组前和重组后时期的早期暗能量

暗能量可以在红移中发挥作用 $z\gg \mathcal{哦}(1)$. 许多精髓模型拥有标度或吸引子解决方案，其中暗能量的部分遵循宇宙膨胀之前时期的主要成分，或者相变可能发生在接近物质辐射相等的时间。围绕物质辐射平等的不可忽略的早期暗能量 (EDE) 部分可能有助于缓解众所周知的$H_0$紧张。在这项工作中，我们使用两种方法来限制 EDE 的比例：首先，我们使用流体参数化来模拟过去主要成分的高原。另一种层析成像方法限制了分级红移间隔中的 EDE 密度。后者使我们能够重建${\mathrm{\Omega }}_{德}(z)$在宇宙微波背景 (CMB) 光子解耦之前和之后。我们使用了2018 年普朗克数据、Ia 型超新星 (SNIa) 的万神殿汇编、星系团数据、SH0ES 对 SNIa 绝对星等的先验，以及来自$\mathrm{孩子们}+\mathrm{维京人}\text{-}450$和 DES-Y1。当我们使用模拟背景高原的最小参数化时，EDE 对当前的宇宙张力影响很小。我们展示了当 EDE 的声速允许变化时，对 EDE 分数的约束如何显着减弱。通过我们的分箱分析，我们对 CMB 解耦时间周围的 EDE 分数施加了非常严格的限制，$\lesssim 0.4\%$ 在 $2\sigma$ cl 我们确认了先前的结果，即在辐射主导的时代中，显着的 EDE 部分会放松 $H_0$ 紧张，但往往会加剧紧张 ${\sigma }_8$. 随后在物质主导时代出现 EDE 有助于缓解这个问题。当在拟合分析中同时考虑 SH0ES 先验和弱透镜数据时，结合来自 CMB、SNIa 和重子声学振荡的数据，EDE 分数被限制为$\lesssim 2.6\%$ 在辐射主导的时代， $\lesssim 1.5\%$ 在红移范围内 $z\in (100,1000)$ 在 $2\sigma$ cl 两种张力仍然具有统计显着性 $～2\mathrm{——}3\sigma$ CL