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arXiv 1301.3777astro-ph.CO
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非高斯性和CMB像差和多普勒

Non-Gaussianity and CMB aberration and Doppler

Riccardo Catena, Michele Liguori, Alessio Notari, Alessandro Renzi

摘要:

观察者相对于CMB静止坐标系的特殊运动会引起所观察光子到达方向的偏转(也称为CMB像差)和所测量光子频率的多普勒频移。因此,像差和多普勒效应引起所观察到的CMB温度图的谐波系数之间的非平凡的相关性。在本文中,我们研究这些相关性是否产生非高斯估计$f_{NL}$的偏见。我们进行这种分析模拟大量的温度图与普朗克一样的分辨率(lmax $= 2000$)作为不同的实现相同的宇宙学基准模型(WMAP 7 yr)。然后,我们添加到这些地图的畸变和多普勒效应采用修改版本的HEALPix代码。最后,我们评估了泛化的小松,Spergel和Wandelt的非高斯估计所有的模拟地图,无论是当特殊的速度效应已被考虑,当这些现象已被忽略。使用我们的特有的速度值$v/c=1.23 \times 10^{-3}$,我们发现,畸变/多普勒诱导的非高斯信号是最多的宇宙方差$σ$的一半左右的$f_{NL}$在一个完整的天空和切割天空的实验配置,为本地,等边和正交的估计。因此,我们得出结论,当估计$f_{NL}$时,忽略像差和多普勒效应是安全的{ \it,如果}原始映射已经是高斯的。然而,还需要做更多的工作来评估一个包含非高斯性的地图是否会被一个特殊的速度显著扭曲。

英文摘要:

The peculiar motion of an observer with respect to the CMB rest frame induces a deflection in the arrival direction of the observed photons (also known as CMB aberration) and a Doppler shift in the measured photon frequencies. As a consequence, aberration and Doppler effects induce non trivial correlations between the harmonic coefficients of the observed CMB temperature maps. In this paper we investigate whether these correlations generate a bias on Non-Gaussianity estimators $f_{NL}$. We perform this analysis simulating a large number of temperature maps with Planck-like resolution (lmax $= 2000$) as different realizations of the same cosmological fiducial model (WMAP7yr). We then add to these maps aberration and Doppler effects employing a modified version of the HEALPix code. We finally evaluate a generalization of the Komatsu, Spergel and Wandelt Non-Gaussianity estimator for all the simulated maps, both when peculiar velocity effects have been considered and when these phenomena have been neglected. Using the value $v/c=1.23 \times 10^{-3}$ for our peculiar velocity, we found that the aberration/Doppler induced Non-Gaussian signal is at most of about half of the cosmic variance $σ$ for $f_{NL}$ both in a full-sky and in a cut-sky experimental configuration, for local, equilateral and orthogonal estimators. We conclude therefore that when estimating $f_{NL}$ it is safe to ignore aberration and Doppler effects {\it if} the primordial map is already Gaussian. More work is necessary however to assess whether a map which contains Non-Gaussianity can be significantly distorted by a peculiar velocity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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