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arXiv 1012.5036astro-ph.CO
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ISW-tSZ互相关:从纯CMB数据中提取ISW

The ISW-tSZ cross correlation: ISW extraction out of pure CMB data

N. Taburet, C. Hernandez-Monteagudo, N. Aghanim, M. Douspis, R. A. Sunyaev

摘要:

如果暗能量在宇宙膨胀中引入了加速,那么大规模的引力势阱应该会收缩,导致穿过这种结构的CMB光子发生蓝移(集成萨克斯-沃尔夫效应,[ISW])。已知星系团可以探测这些潜在的井。在这些物体中,CMB光子也会经历反康普顿散射离开团簇内介质的热电子,这导致了CMB光谱的特征光谱特征的失真(所谓的热Sunyaev-Zel'dovich效应,[tSZ])。由于ISW和tSZ效应都发生在相同的势阱中,因此它们必须在空间上相关。我们提出了如何通过使用多频率CMB实验中的tSZ效应的频率依赖性,如{ \it Planck},{ \em without},需要使用外部大尺度结构示踪剂数据,可以检测到这种交叉ISW-tSZ信号包含CMB数据的方式。我们发现,通过掩盖低红移集群,散粒噪声水平显着降低,提高信噪比的ISW-tSZ互相关。我们还发现,在l=10时,银河系和河外尘埃的残余物必须保持在~0.04 μ K^2的水平或以下,这个极限比{ \it普朗克}对前景减法的预期低几倍。如果实现了这一点,宇宙微波背景辐射对ISW-tSZ互相关的观测也应该为暗能量的存在和密度扰动的幅度提供独立的探测。

英文摘要:

If Dark Energy introduces an acceleration in the universal expansion then large scale gravitational potential wells should be shrinking, causing a blueshift in the CMB photons that cross such structures (Integrated Sachs-Wolfe effect, [ISW]). Galaxy clusters are known to probe those potential wells. In these objects, CMB photons also experience inverse Compton scattering off the hot electrons of the intra-cluster medium, and this results in a distortion with a characteristic spectral signature of the CMB spectrum (the so-called thermal Sunyaev-Zel'dovich effect, [tSZ]). Since both the ISW and the tSZ effects take place in the same potential wells, they must be spatially correlated. We present how this cross ISW-tSZ signal can be detected in a CMB-data contained way by using the frequency dependence of the tSZ effect in multi frequency CMB experiments like {\it Planck}, {\em without} requiring the use of external large scale structure tracers data. We find that by masking low redshift clusters, the shot noise level decreases significantly, boosting the signal to noise ratio of the ISW--tSZ cross correlation. We also find that galactic and extragalactic dust residuals must be kept at or below the level of ~0.04 muK^2 at l=10, a limit that is a factor of a few below {\it Planck}'s expectations for foreground subtraction. If this is achieved, CMB observations of the ISW-tSZ cross correlation should also provide an independent probe for the existence of Dark Energy and the amplitude of density perturbations.

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