Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications
Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications
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DOI：
10.1093/mnras/staa332
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发表时间：
2019-10
影响因子：
4.8
通讯作者：
S. Yasini;E. Pierpaoli
中科院分区：
文献类型：
--
作者：
S. Yasini;E. Pierpaoli
在太阳系的框架下，多普勒效应和像差效应在宇宙微波背景温度谱和偏振功率谱中以模耦合的形式引起失真，从而对由移动的观测者得出的统计量产生偏差。我们探讨了这些偏差的几个方面，并密切关注它们对CMB极化的影响，这是以前没有详细研究过的。我们在这里介绍的一个潜在的重要偏差是增强方差--这是由观测者的运动引起的宇宙方差的一个附加项。尽管这一附加项对于全天实验来说可以忽略不计，但在部分天空实验中，它可以达到标准宇宙方差(σ)的10%(温度)到20%(偏振)。此外，我们还研究了运动诱导功率和宇称不对称性在TT、EE和TE中的意义，以及在全天TTTEEE进行的宇宙学参数估计中可能引起的偏差。利用类似普朗克的模拟，我们发现我们的局域运动在CMB温度和极化功率谱中引起了大范围角尺度的半球不对称性，但这并不意味着宇宙学参数有任何显著的宇称不对称性或位移。最后，我们展望了测量太阳系速度的前景。CMB在未来的实验中将通过模式耦合引起的多普勒和像差效应。利用CMB的TT、EE和TE功率谱(最高可达ℓ=4000)，西蒙斯天文台和CMB-S4可以分别在8.5σ和20σ对我们的局地速度进行与偶极无关的测量。
In the frame of the Solar system, the Doppler and aberration effects cause distortions in the form of mode couplings in the cosmic microwave background (CMB) temperature and polarization power spectra and, hence, impose biases on the statistics derived by the moving observer. We explore several aspects of such biases and pay close attention to their effects on CMB polarization, which, previously, have not been examined in detail. A potentially important bias that we introduce here is boost variance—an additional term in cosmic variance, induced by the observer’s motion. Although this additional term is negligible for whole-sky experiments, in partial-sky experiments it can reach 10 per cent (temperature) to 20 per cent (polarization) of the standard cosmic variance (σ). Furthermore, we investigate the significance of motion-induced power and parity asymmetries in TT, EE, and TE as well as potential biases induced in cosmological parameter estimation performed with whole-sky TTTEEE. Using Planck-like simulations, we find that our local motion induces $\sim 1\!-\!2 {{\ \rm per\ cent}}$ hemispherical asymmetry in a wide range of angular scales in the CMB temperature and polarization power spectra; however, it does not imply any significant amount of parity asymmetry or shift in cosmological parameters. Finally, we examine the prospects of measuring the velocity of the Solar system w.r.t. the CMB with future experiments via the mode coupling induced by the Doppler and aberration effects. Using the CMB TT, EE, and TE power spectra up to ℓ = 4000, the Simons Observatory and CMB-S4 can make a dipole-independent measurement of our local velocity, respectively, at 8.5σ and 20σ.