2002/06/30 by H. K. Eriksen, A. J. Banday, K. M. Górski +1 · 1 citation
Physics and Astronomy · #A priori and a posteriori #Astrophysics and Cosmic Phenomena #Correlation #Correlation function (quantum field theory) #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Gaussian #Monte Carlo method #Noise (video) #Simple (philosophy) #Sky #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021264
published as Astron.Astrophys. 395 (2002) 409-416 · 7 pages, 2 figures, accepted by A&A; Several references added, three new paragraphs with additional information and several typographical details fixed
arxiv created 2002/09/03 · openalex publication_date 2002/11/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We calculate the two-, three- and (for the first time) four-point correlation functions of the COBE-DMR 4-year sky maps, and search for evidence of non-Gaussianity by comparing the data to Monte Carlo-simulations of the functions. The analysis is performed for the 53 and 90 GHz channels, and five linear combinations thereof. For each map, we simulate an ensemble of 10 000 Gaussian realizations based on an a priori best-fit scale-invariant cosmological power spectrum, the DMR beam pattern and instrument-specific noise properties. Each observed COBE-DMR map is compared to the ensemble using a simple statistic, itself calibrated by simulations. In addition, under the assumption of Gaussian fluctuations, we find explicit expressions for the expected values of the four-point functions in terms of combinations of products of the two-point functions, then compare the observed four-point statistics to those predicted by the observed two-point function, using a redefined statistic. Both tests accept the hypothesis that the DMR maps are consistent with Gaussian initial perturbations.