COBE-DMR constraints on the nonlinear coupling parameter: a wavelet based method
Abstract
Nonlinearity introduced in slow-roll inflation will produce weakly non-Gaussian CMB temperature fluctuations. We have simulated non-Gaussian large scale CMB maps (including COBE-DMR constraints) introducing an additional quadratic term in the gravitational potential.The amount of nonlinearity being controlled by the so called nonlinear coupling parameter f_{nl}. An analysis based on the Spherical Mexican Hat wavelet was applied to these and to the COBE-DMR maps. Skewness values obtained at several scales were combined into a Fisher discriminant. Comparison of the Fisher discriminant distributions obtained for different nonlinear coupling parameters with the COBE-DMR values, sets a constraint of abs(f_{nl})<1100 at the 68% confidence level. This new constraint being tighter than the one previously obtained by using the bispectrum by Komatsu et al. (2002).
Keywords
Cite
@article{arxiv.astro-ph/0211399,
title = {COBE-DMR constraints on the nonlinear coupling parameter: a wavelet based method},
author = {L. Cayon and E. Martinez-Gonzalez and F. Argueso and A. J. Banday and K. M. Gorski},
journal= {arXiv preprint arXiv:astro-ph/0211399},
year = {2009}
}
Comments
accepted for publication in MNRAS