The integrated bispectrum as a test of CMB non-Gaussianity: detection power and limits on f_NL with WMAP data
The integrated bispectrum as a test of CMB non-Gaussianity: detection power and limits on f_NL with WMAP data
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作为 CMB 非高斯性测试的积分双谱：WMAP 数据的检测能力和 f_NL 限制
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
N. Vittorio
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作者：
P. Cabella;F. Hansen;M. Liguori;D. Marinucci;S. Matarrese;L. Moscardini;N. Vittorio
我们提出了一种快速有效的宇宙微波背景（CMB）温度各向异性双谱统计，以约束根据非线性耦合参数 f_NL 测量的原始非高斯信号的幅度。我们展示了该方法如何通过关注非高斯信号更集中的多极配置的子集来实现显着的计算优势。测试的检测能力随着最大多极大致线性增加，如没有噪声和间隙的实验的理想情况所示。对于完整双谱，CPU 时间缩放为 l_{max}^3 而不是 l_{max}^5，对于普朗克分辨率 l_{max} sim 3000 意味着与完整双谱分析相比，速度提高了 10^7 倍，精度损失较小。我们发现银河切割的引入部分破坏了配置的最优性，这需要在未来进行处理。我们发现，对于 l_{max}=2000 的理想实验，可以在 1 sigma 处获得 f_{NL}<8 的上限。对于 WMAP 实验的情况，如果不存在银河切割，我们将能够限制 |f_{NL}|<40。使用带有银河切割的真实数据，我们得到的估计值为 -80
We propose a fast and efficient bispectrum statistic for Cosmic Microwave Background (CMB) temperature anisotropies to constrain the amplitude of the primordial non-Gaussian signal measured in terms of the non-linear coupling parameter f_NL. We show how the method can achieve a remarkable computational advantage by focussing on subsets of the multipole configurations, where the non-Gaussian signal is more concentrated. The detection power of the test, increases roughly linearly with the maximum multipole, as shown in the ideal case of an experiment without noise and gaps. The CPU-time scales as l_{max}^3 instead of l_{max}^5 for the full bispectrum which for Planck resolution l_{max} sim 3000 means an improvement in speed of a factor 10^7 compared to the full bispectrum analysis with minor loss in precision. We find that the introduction of a galactic cut partially destroys the optimality of the configuration, which will then need to be dealt with in the future. We find for an ideal experiment with l_{max}=2000 that upper limits of f_{NL}<8 can be obtained at 1 sigma. For the case of the WMAP experiment, we would be able to put limits of |f_{NL}|<40 if no galactic cut were present. Using the real data with galactic cut, we obtain an estimate of -80