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Searching for Integrated Sachs–Wolfe Effect from Fermi-LAT diffuse γ-ray map
Physics of the Dark Universe ( IF 5.0 ) Pub Date : 2020-05-11 , DOI: 10.1016/j.dark.2020.100585
Xiu-Hui Tan , Ji-Ping Dai , Jun-Qing Xia

In this paper, we estimate the cross-correlation power spectra between the Planck 2018 cosmic microwave background (CMB) temperature anisotropy map and the unresolved γ-ray background (UGRB) from the 9-years Fermi-Large Area Telescope (LAT) data. In this analysis, we use up to nine energy bins over a wide energy range of [0.631, 1000] GeV from the Fermi-LAT UGRB data. Firstly, we find that the Fermi data with the energy ranges [1.202, 2.290] GeV and [17.38, 36.31] GeV show the positive evidence for the Integrated Sachs-Wolfe (ISW) effect at 1.8σ confidence level, and the significance would be increased to 2.7σ when using these two energy bins together. Secondly, we apply the single power-law model to normalize the amplitude and use all the nine Fermi energy bins to measure the significance of the ISW effect, we obtained Aamp=0.95±0.53 (68% C.L.). For the robustness test, we implement a null hypothesis by randomizing the Fermi mock maps of nine energy bins and obtain the non-detection of ISW effect, which confirms that the ISW signal comes from the Fermi-LAT diffuse γ-ray data and is consistent with the standard ΛCDM model prediction essentially. We use a cross-correlation coefficient to show the relation between different energy bins. Furthermore, we vary the cut ranges |b| of galactic plane on the mask of Fermi map and carefully check the consequent influence on the ISW signal detection.



中文翻译:

费米-LAT扩散中寻找综合的萨克斯-沃尔夫效应γ射线图

在本文中,我们估计了Planck 2018宇宙微波背景(CMB)温度各向异性图与未解析图之间的互相关功率谱γ9年费米-大面积望远镜(LAT)数据得出的X射线背景(UGRB)。在此分析中,根据费米-LAT UGRB数据,我们在[ 0.631,1000 ] GeV的宽能量范围内使用了多达9个能量仓。首先,我们发现能量范围为[1.202,2.290] GeV和[17.38,36.31] GeV的费米数据显示了萨克斯-沃尔夫综合(ISW)效应的积极证据。1个8σ 置信水平,其重要性将提高到 27σ当同时使用这两个能量箱时。其次,我们使用单幂定律模型对幅度进行归一化,并使用所有9个费米能量箱来测量ISW效应的显着性,一种安培=095±053(68%CL)。对于鲁棒性测试,我们通过随机化九个能量箱的费米模拟图来实现零假设,并获得未检测到ISW效应的结果,这证实了ISW信号来自费米-LAT扩散γ射线数据并符合标准 ΛCDM模型预测本质上。我们使用互相关系数来显示不同能量仓之间的关系。此外,我们改变切割范围|b|费米地图的蒙版上检查银河平面,并仔细检查其对ISW信号检测的影响。

更新日期:2020-05-11
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