Signal-to-noise eigenmode analysis of the two-year COBE maps.
Signal-to-noise eigenmode analysis of the two-year COBE maps.
复制标题
两年 COBE 图的信噪比本征模分析。
DOI：
10.1103/physrevlett.74.4369
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发表时间：
1994
影响因子：
8.6
通讯作者：
R. Bond
中科院分区：
文献类型：
--
作者：
J.;R. Bond
为了测试宇宙微波背景波动理论，自然会在像素幅度的线性组合的不相关基础上展开各向异性图-噪声和信号在统计上都是独立的。这些$S/N$本征模对于各向异性实验的快速贝叶斯分析是必不可少的，这里应用于最近发布的两年的COBE{\it DMR}图和{\it Firs}图。一个带总功率和光谱倾斜的双参数模型很好地描述了基于暴涨的理论。$53，90，31$$a$+$b$GHz和170 GHz映射的频带功率是一致的，$(1.1\pm0.1)\x 10^-5}^{1/2}$，并且在很大程度上与倾斜和(尖锐)$S/N$-滤波的程度无关。此外，经过最优的$S/N$滤波后，{itDMR}图显示了相同的与倾斜无关的大尺度特征和相关函数。未过滤的$53$$+$b$指数$\nu_{\Delta T}+1$是$1.4\pm 0.4$；增加$S/N$-过滤得到(1-1-1.2)$\pm$0.5的较大区域，跳到(1.4--1.6)$\pm$0.5，然后下降到0.8，较高的值显然是由$S/N$-不符合单倾斜模型的功率谱数据点驱动的。这些指数与通货膨胀率($0.8-1.2)很好地兼容，但并不是压倒性的。
To test a theory of cosmic microwave background fluctuations, it is natural to expand an anisotropy map in an uncorrelated basis of linear combinations of pixel amplitudes --- statistically-independent for both the noise and the signal. These $S/N$-eigenmodes are indispensible for rapid Bayesian analyses of anisotropy experiments, applied here to the recently-released two-year COBE {\it dmr} maps and the {\it firs} map. A 2-parameter model with an overall band-power and a spectral tilt $\nu_{\Delta T}$ describes well inflation-based theories. The band-powers for {\it all} the {\it dmr} $53,90,31$ $a$+$b$ GHz and {\it firs} 170 GHz maps agree, $\{(1.1\pm 0.1)\times 10^{-5}\}^{1/2}$, and are largely independent of tilt and degree of (sharp) $S/N$-filtering. Further, after optimal $S/N$-filtering, the {\it dmr} maps reveal the same tilt-independent large scale features and correlation function. The unfiltered {\it dmr} $53$ $a$+$b$ index $\nu_{\Delta T}+1$ is $1.4\pm 0.4$; increasing the $S/N$-filtering gives a broad region at (1.0--1.2)$\pm$0.5, a jump to (1.4--1.6)$\pm$0.5, then a drop to 0.8, the higher values clearly seen to be driven by $S/N$-power spectrum data points that do not fit single-tilt models. These indices are nicely compatible with inflation values ($\sim$0.8--1.2), but not overwhelmingly so.