用地面laser干涉仪网络探测随机引力波背景的各向异性
Probing the anisotropies of a stochastic gravitational-wave background using a network of ground-based laser interferometers
摘要：
我们提出了一个最大似然分析，估计在各向异性的随机引力波背景下使用地面激光干涉仪的功率的角分布。标准的各向同性和引力波辐射计搜索（最佳点源）恢复为特殊的限制情况。角分布可以相对于天空中的任何基函数进行分解，并且单基线互相关分析很容易扩展到三个或更多个探测器的网络，即多基线。球谐分解，它提供了最大似然估计的多极矩的引力波天空，详细说明。我们还讨论：（i）估计器的协方差矩阵及其与干涉仪网络的探测器响应的关系，（ii）用于正则化来自测量的天空图的探测器响应的去卷积的奇异值分解方法，（iii）通过包括多个基线获得的灵敏度的预期增加，（iv）该方法应用于由点源和双源组成的模拟数据时的数值结果。这个一般的方法和标准的各向同性和辐射计搜索之间的比较，在整个过程中，与现有的文献随机背景搜索。
英文摘要：
We present a maximum-likelihood analysis for estimating the angular distribution of power in an anisotropic stochastic gravitational-wave background using ground-based laser interferometers. The standard isotropic and gravitational-wave radiometer searches (optimal for point sources) are recovered as special limiting cases. The angular distribution can be decomposed with respect to any set of basis functions on the sky, and the single-baseline, cross-correlation analysis is easily extended to a network of three or more detectors-that is, to multiple baselines. A spherical harmonic decomposition, which provides maximum-likelihood estimates of the multipole moments of the gravitational-wave sky, is described in detail. We also discuss: (i) the covariance matrix of the estimators and its relationship to the detector response of a network of interferometers, (ii) a singular-value decomposition method for regularizing the deconvolution of the detector response from the measured sky map, (iii) the expected increase in sensitivity obtained by including multiple baselines, and (iv) the numerical results of this method when applied to simulated data consisting of both point-like and di#use sources. Comparisions between this general method and the standard isotropic and radiometer searches are given throughout, to make contact with the existing literature on stochastic background searches.
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