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[论文解读] Is the $w_0w_a$CDM cosmological parameterization evidence for dark energy dynamics partially caused by the excess smoothing of Planck CMB anisotropy data?

Chan‐Gyung Park, Javier de Cruz Pérez|arXiv (Cornell University)|Oct 4, 2024
Cosmology and Gravitation Theories被引用 13
一句话总结

作者在 Planck 2018 数据和非 CMB 数据下，测试了平坦动态暗能量模型 w0-wa CDM，有无可变透镜参数 AL；他们发现对暗能量动力学的证据较为温和，且 AL>1，表明 Planck 平滑化可能对动力学信号有贡献。

ABSTRACT

We study the performance of the spatially-flat dynamical dark energy (DE) $w_0w_a$CDM parameterization, with redshift-dependent DE fluid equation of state parameter $w(z) = w_0 + w_a z/(1+z)$, with and without a varying CMB lensing consistency parameter $A_L$, against Planck cosmic microwave background (CMB) data (P18 and lensing) and a combination of non-CMB data composed of baryonic acoustic oscillation (BAO) measurements that do not include DESI BAO data, Pantheon+ type Ia supernovae (SNIa) observations, Hubble parameter [$H(z)$] measurements, and growth factor ($fσ_8$) data points. From our most restrictive data set, P18+lensing+non-CMB, for the $w_0w_a$CDM+$A_L$ parameterization, we obtain $w_0=-0.879\pm 0.060$, $w_a=-0.39^{+0.26}_{-0.22}$, the asymptotic limit $w(z\to\infty) = w_0+w_a=-1.27^{+0.20}_{-0.17}$, and $A_L=1.078^{+0.036}_{-0.040}$ (all $1σ$ errors). This joint analysis of CMB and non-CMB data favors DE dynamics over a cosmological constant at $\sim 1σ$ and $A_L>1$ at $\sim 2σ$, i.e. more smoothing of the Planck CMB anisotropy data than is predicted by the best-fit model. For the $w_0w_a$CDM parameterization with $A_L=1$ the evidence in favor of DE dynamics is larger, $\sim 2σ$, suggesting that at least part of the evidence for DE dynamics comes from the excess smoothing of the Planck CMB anisotropy data. For the $w_0w_a$CDM parameterization with $A_L=1$, there is a difference of $2.8σ$ between P18 and non-CMB cosmological parameter constraints and $2.7σ$ between P18+lensing and non-CMB constraints. When $A_L$ is allowed to vary these tensions reduced to $1.9σ$ and $2.1σ$ respectively. Our P18+lensing+non-CMB data compilation positively favors the $w_0w_a$CDM parameterization without and with a varying $A_L$ parameter over the flat $Λ$CDM model, and $w_0w_a$CDM+$A_L$ is also positively favored over $w_0w_a$CDM.

研究动机与目标

  • 评估当与非-CMB 数据结合时，w0-wa CDM 动态暗能量参数化是否比 ΛCDM 更好地拟合 Planck CMB 数据。
  • 研究是否允许变化的 CMB 镜像参数 AL 能否改善跨数据集的一致性和拟合。
  • 在有无 AL 的情况下，评估相对于 ΛCDM 的统计偏好在数据组合中的变化。
  • 检验是否有动力学证据部分来自 Planck CMB 向各向同性数据的额外平滑效应。

提出的方法

  • 使用 CAMB/COSMOMC (Oct 2018) 计算预测并进行 MCMC 参数估计。
  • 用 w(z)=w0+w_a z/(1+z) 来参数化暗能量，并测试 AL=1 与 AL 自由（AL 在 [0,10]）。
  • 将 Planck 2018 TT,TE,EE+lowE (P18) 与 Planck lensing 数据以及非-CMB 数据（BAO、Pantheon+ SNIa、H(z)、fσ8）结合。
  • 约束平坦 ΛCDM、平坦 w0-wa CDM 以及 平坦 w0-wa CDM+ AL 模型，报告均值、68%（或 95%）置信区间，以及推导参数（H0、Ωm、σ8）。
  • research_questionsPrereqs_1_or_3_dynamics_and_smoothing_queries_1
  • assess_dynamics_significance
  • assess_AL_impact_on_consistency_and_fit
  • determine_role_of_planck_smoothing_in_dynamics_evidence
Figure 1: One-dimensional likelihoods and 1 $\sigma$ and $2\sigma$ likelihood confidence contours of flat $w_{0}w_{a}$ CDM model parameters favored by non-CMB, P18, and P18+non-CMB data sets. We do not show $\tau$ and $n_{s}$ , which are fixed in the non-CMB data analysis. The horizontal or vertical
Figure 1: One-dimensional likelihoods and 1 $\sigma$ and $2\sigma$ likelihood confidence contours of flat $w_{0}w_{a}$ CDM model parameters favored by non-CMB, P18, and P18+non-CMB data sets. We do not show $\tau$ and $n_{s}$ , which are fixed in the non-CMB data analysis. The horizontal or vertical

实验结果

研究问题

  • RQ1当分析 Planck 2018 数据加上非-CMB 数据时，w0-wa CDM 参数化是否提供相对于 ΛCDM 的暗能量动力学证据？
  • RQ2引入可变 AL 参数是否改善 CMB 与非-CMB 约束的一致性并提升拟合质量？
  • RQ3在包含非-CMB 数据与仅 Planck 数据时，对 w0、wa 和 AL 的约束有何变化？
  • RQ4是否有部分被感知的动力学证据归因于 Planck 向 CMB 向各向同性的额外平滑？

主要发现

  • 对于 P18+lensing+non-CMB 数据采用 w0-wa CDM+ AL，我们得到 w0= -0.879 ± 0.060, wa = -0.39^{+0.26}_{-0.22}, 和 AL = 1.078^{+0.036}_{-0.040} (1σ)。
  • 高红移极限下的 w0+wa = -1.27^{+0.20}_{-0.17} 且 AL>1 在约 2σ 下受偏好；在 AL 自由时，动力学暗能量相对于 ΛCDM 的偏好约为 1σ。
  • 在没有 AL（AL=1）时，动力学暗能量的证据更强（约 2σ），表明部分动力学信号可能来自 Planck 数据的平滑处理。
  • 允许 AL 变化可降低 CMB 与非-CMB 数据之间的张力（P18 vs 非-CMB 与 P18+lensing vs 非-CMB）从约 2σ 降至约 1.9–2.1σ。
  • 与 ΛCDM 相比，w0-wa CDM+ AL 在信息准则上被正向偏好（ΔDIC ≈ -4.37, ΔAIC ≈ -5.00，对 P18+lensing+non-CMB 数据）。
  • 总体而言，结果表明 Planck 数据中的过度弱透镜平滑可能有助于观测到的动力学信号，尽管证据仍然适度。
Figure 2: One-dimensional likelihoods and 1 $\sigma$ and $2\sigma$ likelihood confidence contours of flat $w_{0}w_{a}$ CDM model parameters favored by non-CMB, P18+lensing, P18+lensing+non-CMB data sets. We do not show $\tau$ and $n_{s}$ , which are fixed in the non-CMB data analysis. The horizontal
Figure 2: One-dimensional likelihoods and 1 $\sigma$ and $2\sigma$ likelihood confidence contours of flat $w_{0}w_{a}$ CDM model parameters favored by non-CMB, P18+lensing, P18+lensing+non-CMB data sets. We do not show $\tau$ and $n_{s}$ , which are fixed in the non-CMB data analysis. The horizontal

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