Using inpainting to construct accurate cut-sky CMB estimators
| Autor: | Gruetjen, H. F., Fergusson, J. R., Liguori, M., Shellard, E. P. S. |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Phys. Rev. D 95, 043532 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevD.95.043532 |
| Popis: | The direct evaluation of manifestly optimal, cut-sky CMB power spectrum and bispectrum estimators is numerically very costly, due to the presence of inverse-covariance filtering operations. This justifies the investigation of alternative approaches. In this work, we mostly focus on an inpainting algorithm that was introduced in recent CMB analyses to cure cut-sky suboptimalities of bispectrum estimators. First, we show that inpainting can equally be applied to the problem of unbiased estimation of power spectra. We then compare the performance of a novel inpainted CMB temperature power spectrum estimator to the popular apodised pseudo-$C_l$ (PCL) method and demonstrate, both numerically and with analytic arguments, that inpainted power spectrum estimates significantly outperform PCL estimates. Finally, we study the case of cut-sky bispectrum estimators, comparing the performance of three different approaches: inpainting, apodisation and a novel low-l leaning scheme. Providing an analytic argument why the local shape is typically most affected we mainly focus on local type non-Gaussianity. Our results show that inpainting allows to achieve optimality also for bispectrum estimation, but interestingly also demonstrate that appropriate apodisation, in conjunction with low-l cleaning, can lead to comparable accuracy. Comment: 21 pages, 10 figures |
| Databáze: | arXiv |
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