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arXiv 2406.06296astro-ph.CO
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探索Planck PR3与ACT DR4之间的差异

Exploring the discrepancy between Planck PR3 and ACT DR4

Dhiraj Kumar Hazra, Benjamin Beringue, Josquin Errard, Arman Shafieloo, George F. Smoot

AI总结:

本文通过参数化和非参数方法比较Planck PR3与ACT DR4的原初功率谱,发现二者在0.08–0.16 Mpc⁻¹尺度上因ACT内部谱指数偏好变化而产生2–3σ张力,提示该差异更可能源于系统效应而非新物理。

摘要:

我们探索了Planck PR3与阿塔卡马宇宙学望远镜(ACT)DR4数据之间不一致的尺度与程度。Planck与ACT数据在对应于多极矩ℓ≈600–2500的尺度上的温度各向异性数据存在大量重叠,同时Planck覆盖更大的角尺度,ACT覆盖更小的角尺度,二者互为补充。由于同一宇宙学模型应当支配所有尺度上的各向异性功率谱,我们在原初功率谱中探究这一不一致。我们采用一种允许谱指数变化的幂律原初谱参数化形式。我们还使用非参数方法从Planck和ACT温度数据中重建原初功率谱。我们发现不一致存在于0.08–0.16 Mpc⁻¹的尺度范围内,在该范围内ACT温度数据偏好尺度不变或蓝色谱。在此窗口更大和更小的尺度上,ACT数据强烈偏好红色谱指数,这与Planck一致。这种谱指数的变化可以在不使用Planck数据的情况下,在ACT数据中以2σ置信水平被识别出来,表明这一张力是由ACT数据内部对谱指数的不同偏好所驱动。加入Planck数据直至中等尺度(ℓ≤650)后,该显著性提高到3σ。鉴于Planck与ACT在0.08–0.16 Mpc⁻¹范围内存在大量重叠,并考虑到不同Planck温度谱和偏振谱之间的内部一致性,新物理作为该张力解决方案的空间仍然有限。我们的结果——对谱指数中间过渡的强烈偏好以及该偏好在不同数据组合中的变化——表明系统效应可能被误认为是由不同非标准宇宙学过程产生的新物理。

英文摘要:

We explore the scales and the extent of disagreement between $Planck$ PR3 and Atacama Cosmology Telescope (ACT) DR4 data. $Planck$ and ACT data have substantial overlap in the temperature anisotropy data between scales corresponding to multipoles $\ell\simeq 600-2500$ with complementing coverage of larger angular scales by $Planck$ and smaller angular scales by ACT. Since the same cosmology should govern the anisotropy spectrum at all scales, we probe this disagreement in the primordial power spectrum. We use a parametric form of power law primordial spectrum that allows changes in the spectral tilt. We also reconstruct the primordial spectrum with a non-parametric method from both $Planck$ and ACT temperature data. We find the disagreement exists within scales 0.08 - 0.16 ${\rm Mpc}^{-1}$ where ACT temperature data prefers a scale invariant/blue spectrum. At scales larger and smaller than this window, ACT data strongly prefers a red tilt, which is consistent with $Planck$. This change in the spectral tilt can be identified in the ACT data at 2$σ$ C.L. without using $Planck$ data, indicating that the tension is driven by different preferences for tilts within the ACT data. The addition of $Planck$ data up to intermediate scales ($\ell\le650$) increases this significance to 3$σ$. Given the large overlap between $Planck$ and ACT within 0.08 - 0.16 ${\rm Mpc}^{-1}$ and considering the internal consistency between different $Planck$ temperature and polarization spectra, the scope of new physics as a solution to the tension remains limited. Our results -- a strong preference for an intermediate transition in spectral tilt and the variation of this preference in different data combinations -- indicate that systematic effects can be misperceived as new physics emerging from different non-standard cosmological processes.

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