模拟全天干涉观测
Simulating full-sky interferometric observations
摘要：
孔径阵列干涉仪，例如为平方公里阵列（SKA）提出的干涉仪，将看到整个天空，因此模拟可见光的标准方法将不适用，因为它依赖于仅对小视场有效的切平面近似。我们推导出干涉公式在真正的，球谐和小波空间，包括整个天空的贡献，不依赖于任何切平面近似。本文提出了一种快速小波方法来模拟全天空条件下干涉仪观测到的大气湍流。采用快速小波方法计算可见光强度，适合于主波束和天空强度在小波基上的稀疏表示。因此，快速小波方法表现出优越的计算复杂性的实和球谐空间的方法，并可以在相当低的计算成本进行，同时只引入可忽略不计的误差模拟vibrations。低分辨率干涉观测模拟使用所有的方法来比较它们的性能，表明快速小波方法是大约三倍的速度比其他方法，这些低分辨率的模拟。实数和球谐空间方法的计算负担使得这些技术对于更高分辨率的模拟在计算上不可行。高分辨率的干涉观测模拟使用快速小波方法，演示和验证这种方法的应用，以现实的模拟。快速小波方法估计提供了一个大于十倍的减少执行时间相比，这些高分辨率的模拟的其他方法。
英文摘要：
Aperture array interferometers, such as that proposed for the Square Kilometre Array (SKA), will see the entire sky, hence the standard approach to simulating visibilities will not be applicable since it relies on a tangent plane approximation that is valid only for small fields of view. We derive interferometric formulations in real, spherical harmonic and wavelet space that include contributions over the entire sky and do not rely on any tangent plane approximations. A fast wavelet method is developed to simulate the visibilities observed by an interferometer in the full-sky setting. Computing visibilities using the fast wavelet method adapts to the sparse representation of the primary beam and sky intensity in the wavelet basis. Consequently, the fast wavelet method exhibits superior computational complexity to the real and spherical harmonic space methods and may be performed at substantially lower computational cost, while introducing only negligible error to simulated visibilities. Low-resolution interferometric observations are simulated using all of the methods to compare their performance, demonstrating that the fast wavelet method is approximately three times faster that the other methods for these low-resolution simulations. The computational burden of the real and spherical harmonic space methods renders these techniques computationally infeasible for higher resolution simulations. High-resolution interferometric observations are simulated using the fast wavelet method only, demonstrating and validating the application of this method to realistic simulations. The fast wavelet method is estimated to provide a greater than ten-fold reduction in execution time compared to the other methods for these high-resolution simulations.
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