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 ℓ ≃ 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 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 2σ 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 (ℓ ≤ 650) increases this significance to 3σ. Given the large overlap between Planck and ACT within 0.08–0.16 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.

中文翻译：

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探索普朗克 PR3 和 ACT DR4 之间的差异


我们探讨了普朗克 PR3 和阿塔卡马宇宙学望远镜 （ACT） DR4 数据之间的比例和不一致程度。Planck 和 ACT 数据在对应于多极点 l ≃ 600–2500 的尺度之间的温度各向异性数据中具有很大的重叠，并补充了 Planck 对较大角度尺度和 ACT 对较小角度尺度的覆盖。由于相同的宇宙学应该支配所有尺度的各向异性谱，因此我们在原始功率谱中探索这种不一致。我们使用幂律原始谱的参数形式，允许频谱倾斜的变化。我们还使用非参数方法从 Planck 和 ACT 温度数据中重建原始光谱。我们发现在 0.08–0.16 Mpc-1 的尺度内存在差异，其中 ACT 温度数据更喜欢尺度不变/蓝色光谱。在大于和小于此窗口的尺度上，ACT 数据强烈倾向于红色倾斜，这与普朗克模式一致。光谱倾斜的这种变化可以在 2σ C.L. 的 ACT 数据中识别出来，而无需使用普朗克数据，这表明张力是由 ACT 数据中对倾斜的不同偏好驱动的。将普朗克数据添加到中间尺度 （l ≤ 650） 将这一显著性增加到 3σ。鉴于普朗克和 ACT 之间在 0.08–0.16 Mpc-1 之间的较大重叠，并且考虑到不同普朗克温度和极化光谱之间的内部一致性，作为张力解决方案的新物理学的范围仍然有限。我们的研究结果——强烈倾向于光谱倾斜的中间转变，以及这种偏好在不同数据组合中的变化——表明系统效应可能被误解为来自不同非标准宇宙学过程的新物理学。