COBE-DMR constraints on the non-linear coupling parameter: a wavelet based method
Abstract
Non-linearity introduced in slow-roll inflation will produce weakly non-Gaussian cosmic microwave background (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 non-linearity is controlled by the so-called non-linear coupling parameter fnl. 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 non-linear coupling parameters with the COBE-DMR values sets a constraint of |fnl| < 1100 at the 68 per cent confidence level. This new constraint is tighter than the one previously obtained by using the bispectrum by Komatsu et al.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2003
- DOI:
- 10.1046/j.1365-8711.2003.06269.x
- arXiv:
- arXiv:astro-ph/0211399
- Bibcode:
- 2003MNRAS.339.1189C
- Keywords:
-
- methods: data analysis;
- cosmic microwave background;
- Astrophysics
- E-Print:
- accepted for publication in MNRAS