Searching for dark energy in the matter-dominated era
Searching for dark energy in the matter-dominated era
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DOI：
10.1093/mnras/stab1338
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发表时间：
2020-07
影响因子：
4.8
通讯作者：
P. Bull;M. White;A. Slosar
中科院分区：
文献类型：
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作者：
P. Bull;M. White;A. Slosar
大多数检测动态暗能量 (DE) 特征的努力都集中在后期，即 z ≲ 2，此时 DE 分量开始主导宇宙能量密度。然而，许多涉及动力学 DE 的理论模型都表现出“冻结”状态方程，其中 w → -1 在后期，并在早期过渡到“跟踪”行为（在足够高的红移下 w ≫ -1）。在本文中，我们研究了在后再电离物质主导体系 2 ≲ z ≲ 6 中对大规模结构 (LSS) 调查的背景距离指标的约束是否对此行为敏感，基于在给出足够精确的观测的情况下，DE 分量在该红移范围内应保持可检测到（尽管处于强烈的次主导地位）。使用受 Horndeski（广义标量张量）理论参数空间研究启发的现象学模型，我们展示了现有的 CMB 和 LSS 测量如何在物质主导的时代约束 DE 状态方程，并研究即将进行的星系巡天和 21 厘米强度测绘仪器如何在背景水平上改善这一状况的约束。我们还发现，现有的 CMB 和 LSS 约束与 DESI 的组合已经接近于使用 BAO/星系功率谱测量对 H0 提供最佳可能的约束，并且 LSST 星系样本的光谱跟踪（例如 MegaMapper 或 SpecTel）或阶段 2/PUMA 类强度映射调查（均在 z ≳ 2 处）将为此处考虑的模型类别提供比可比较的宇宙方差有限星系更好的约束z ≲ 1.5 处的测量。
Most efforts to detect signatures of dynamical dark energy (DE) are focused on late times, z ≲ 2, where the DE component begins to dominate the cosmic energy density. Many theoretical models involving dynamical DE exhibit a ‘freezing’ equation of state however, where w → −1 at late times, with a transition to a ‘tracking’ behaviour at earlier times (with w ≫ −1 at sufficiently high redshift). In this paper, we study whether constraints on background distance indicators from large-scale structure (LSS) surveys in the post-reionization matter-dominated regime, 2 ≲ z ≲ 6, are sensitive to this behaviour, on the basis that the DE component should remain detectable (despite being strongly subdominant) in this redshift range given sufficiently precise observations. Using phenomenological models inspired by parameter space studies of Horndeski (generalized scalar-tensor) theories, we show how existing CMB and LSS measurements constrain the DE equation of state in the matter-dominated era, and examine how forthcoming galaxy surveys and 21 cm intensity mapping instruments can improve constraints in this regime at the background level. We also find that the combination of existing CMB and LSS constraints with DESI will already come close to offering the best possible constraints on H0 using BAO/galaxy power spectrum measurements, and that either a spectroscopic follow-up of the LSST galaxy sample (e.g. MegaMapper or SpecTel) or a Stage 2/PUMA-like intensity mapping survey, both at z ≳ 2, would offer better constraints on the class of models considered here than a comparable cosmic variance-limited galaxy survey at z ≲ 1.5.