Planck 2015 results XI. CMB power spectra, likelihoods, and robustness of parameters
Planck 2015 results XI. CMB power spectra, likelihoods, and robustness of parameters
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DOI：
10.1051/0004-6361/201526926
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发表时间：
2016-10-01
影响因子：
6.5
通讯作者：
Zonca, A.
中科院分区：
文献类型：
--
作者：
Aghanim, N.;Arnaud, M.;Zonca, A.
本文介绍了普朗克2015似然性，宇宙微波背景（CMB）温度和偏振波动的2点相关函数的统计描述，解释了相关的不确定性，包括仪器和天体物理性质。它们基于与上一版本相同的混合方法，即，在低多极（l < 30）处的基于像素的似然性和在较高多极处的交叉功率谱的分布的高斯近似。主要的改进是使用了更多更好的处理数据和普朗克极化信息，沿着使用了更详细的前景和仪器不确定性模型。由于分析的数据量增加一倍以上，冗余度增加，因此能够进一步进行一致性检查，并增强对系统性影响的免疫力。它还提高了普朗克的约束能力，特别是在小尺度前景属性方面。前景发射建模方面的进展使得能够保留更大比例的天空，以确定CMB的性质，这也有助于提高光谱的精度。数据处理和仪器建模的改进进一步减少了不确定性。大量的测试建立了可能性结果的鲁棒性和准确性，单独从温度，单独从偏振，以及从它们的组合。对于温度，我们还对仪器对天空的响应进行了真实的端到端模拟的全似然分析，这些模拟被输入到实际的数据处理管道中;这并没有揭示来自残余低水平仪器系统学的偏差。即使在精度和鲁棒性方面有所提高，Lambda CDM宇宙学模型仍然能够很好地拟合普朗克数据。原始标量波动的斜率，n（s），被证实小于单位在普朗克单独超过5西格玛。我们进一步验证了似然结果相对于基线宇宙学特定扩展的稳健性，这些扩展对高多极数据特别敏感。例如，中微子种类的有效数仍然与3.046的规范值相一致。对于这第一次详细分析普朗克偏振光谱，我们集中在高多极的E模式，留下较弱的B模式的分析，以未来的工作。在低多极，我们使用温度图在所有普朗克频率沿着与极化数据的子集。这些数据利用了普朗克的宽频率覆盖范围，以改善CMB和前景发射的分离。在基线Lambda CDM宇宙学中，这需要再电离光学深度tau = 0.078 +/- 0.019，这显着低于在不使用高频数据明确监测尘埃排放的情况下的估计。在高多极，我们检测E极化的残余系统误差，通常在μ K-2水平;因此，我们选择保留温度信息单独为高多极作为推荐的基线，特别是用于测试非最小模型。尽管如此，普朗克的高多极极化光谱已经足够好，可以单独高精度地确定λ CDM模型的参数，这与仅从温度信息独立建立的参数是一致的。
This paper presents the Planck 2015 likelihoods, statistical descriptions of the 2-point correlation functions of the cosmic microwave background (CMB) temperature and polarization fluctuations that account for relevant uncertainties, both instrumental and astrophysical in nature. They are based on the same hybrid approach used for the previous release, i.e., a pixel-based likelihood at low multipoles (l < 30) and a Gaussian approximation to the distribution of cross-power spectra at higher multipoles. The main improvements are the use of more and better processed data and of Planck polarization information, along with more detailed models of foregrounds and instrumental uncertainties. The increased redundancy brought by more than doubling the amount of data analysed enables further consistency checks and enhanced immunity to systematic effects. It also improves the constraining power of Planck, in particular with regard to small-scale foreground properties. Progress in the modelling of foreground emission enables the retention of a larger fraction of the sky to determine the properties of the CMB, which also contributes to the enhanced precision of the spectra. Improvements in data processing and instrumental modelling further reduce uncertainties. Extensive tests establish the robustness and accuracy of the likelihood results, from temperature alone, from polarization alone, and from their combination. For temperature, we also perform a full likelihood analysis of realistic end-to-end simulations of the instrumental response to the sky, which were fed into the actual data processing pipeline; this does not reveal biases from residual low-level instrumental systematics. Even with the increase in precision and robustness, the Lambda CDM cosmological model continues to offer a very good fit to the Planck data. The slope of the primordial scalar fluctuations, n(s), is confirmed smaller than unity at more than 5 sigma from Planck alone. We further validate the robustness of the likelihood results against specific extensions to the baseline cosmology, which are particularly sensitive to data at high multipoles. For instance, the effective number of neutrino species remains compatible with the canonical value of 3.046. For this first detailed analysis of Planck polarization spectra, we concentrate at high multipoles on the E modes, leaving the analysis of the weaker B modes to future work. At low multipoles we use temperature maps at all Planck frequencies along with a subset of polarization data. These data take advantage of Planck's wide frequency coverage to improve the separation of CMB and foreground emission. Within the baseline Lambda CDM cosmology this requires tau = 0.078 +/- 0.019 for the reionization optical depth, which is significantly lower than estimates without the use of high-frequency data for explicit monitoring of dust emission. At high multipoles we detect residual systematic errors in E polarization, typically at the mu K-2 level; we therefore choose to retain temperature information alone for high multipoles as the recommended baseline, in particular for testing non-minimal models. Nevertheless, the high-multipole polarization spectra from Planck are already good enough to enable a separate high-precision determination of the parameters of the Lambda CDM model, showing consistency with those established independently from temperature information alone.