Towards a fast, model-independent Cosmic Microwave Background bispectrum estimator

TL;DR

This paper proposes a fast, flexible, and model-independent method for estimating the CMB bispectrum by decomposing the sphere into patches, enabling efficient non-Gaussianity analysis.

Contribution

It introduces a novel, patch-based bispectrum estimator that is computationally efficient and adaptable for targeted CMB non-Gaussianity measurements.

Findings

Enables quick calculation of the mean bispectrum

Allows exclusion or focus on specific sky regions

Provides a flexible framework for model-independent analysis

Abstract

The measurements of the statistical properties of the Cosmic Microwave Background (CMB) fluctuations enable us to probe the physics of the very early Universe especially at the epoch of inflation. A particular interest lays on the detection of the non-Gaussianity of the CMB as it can constrain the current proposed models of inflation and structure formation, or possibly point out new models. The current approach to measure the degree of non-Gaussianity of the CMB is to estimate a single parameter which is highly model-dependent. The bispectrum is a natural and widely studied tool for measuring the non-Gaussianity in a model-independent way. This paper sets the grounds for a full CMB bispectrum estimator based on the decomposition of the sphere onto projected patches. The mean bispectrum estimated this way can be calculated quickly and is model-independent. This approach is very flexible, allowing exclusion of some patches in the processing or consideration of just a specific region of the sphere.