Probing non-Gaussianities in the CMB on an incomplete sky using surrogates
published: Jan. 23, 2012, recorded: December 2011, views: 99
Report a problem or upload filesIf you have found a problem with this lecture or would like to send us extra material, articles, exercises, etc., please use our ticket system to describe your request and upload the data.
Enter your e-mail into the 'Cc' field, and we will keep you updated with your request's status.
For investigations of CMB data sets, the analysis of Fourier phases has proven to be a useful method, since all potential higher order correlations, which directly point to non-Gaussianities, are contained in the phases and the correlations among them. The method of surrogate maps with shuffled Fourier phases represents one way of analysing the phases. The shuffling approach relies on the orthogonality of the spherical harmonics, which only holds for the full sky. However, astrophysical foreground emission, mainly present in the Galactic plane, are a major challenge in CMB analyses. We demonstrate the feasibility to generate surrogates by Fourier-based methods also for an incomplete data set by transforming the spherical harmonics into a new set of basis functions that are orthonormal on the cut sky. The results show that non-Gaussianities and hemispherical asymmetries in the CMB as identified in several former investigations, can still be detected even when the complete Galactic plane is removed. We conclude that the Galactic plane cannot be the dominant source for these anomalies.
Download slides: nipsworkshops2011_rossmanith_gaussianitites_01.pdf (2.2 MB)
Link this pageWould you like to put a link to this lecture on your homepage?
Go ahead! Copy the HTML snippet !