标题： 两年COBE地图的信噪比本征模分析 显示英文标题

标题： Signal-to-Noise Eigenmode Analysis of the Two-Year COBE Maps

摘要： 为了检验宇宙微波背景涨落的理论，自然会用像素振幅的线性组合的非相关基底展开各向异性图——这种基底对于噪声和信号都是统计独立的。 这些$S/N$-本征模式 对于快速贝叶斯分析各向异性实验至关重要，在这里应用于最近发布的两年期COBE{\it dmr}图以及{\it 首先}图。 一个包含整体频带功率和谱倾斜$\nu_{\Delta T}$的双参数模型很好地描述了基于膨胀的理论。 {\it 所有}频段的功率与{\it dmr} $53,90,31$ $a$ +$b$GHz 和{\it 首先}170 GHz 的地图一致，$\{(1.1\pm 0.1)\times 10^{-5}\}^{1/2}$，并且在很大程度上独立于倾斜角度和（尖锐）$S/N$滤波的程度。 进一步，在最优的 $S/N$-滤波之后， {\it dmr} 图映射揭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 {\it dmr} $53$ $a$ +$b$指数$\nu_{\Delta T}+1$为$1.4\pm 0.4$；增加 $S/N$滤波得到一个宽广区域位于 (1.0--1.2)$\pm$0.5，跳至 (1.4--1.6)$\pm$0.5，然后下降到 0.8，较高的值明显是由不拟合单倾斜模型的数据点$S/N$驱动的。 这些指数与膨胀值（$\sim$0.8--1.2）非常兼容，但不过分如此。 显示英文摘要

摘要： 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.