Observed parity-odd CMB temperature bispectrum

TL;DR

This paper introduces the first experimental constraints on parity-odd non-Gaussianities in the CMB temperature bispectrum using WMAP data, expanding the analysis beyond the traditionally studied parity-even cases.

Contribution

It provides the first constraints on parity-odd bispectrum signals in CMB data and develops a separable modal estimator for these signals.

Findings

Placed constraints on nonlineality parameters of parity-odd tensor non-Gaussianities

Developed a model-independent reconstruction of the parity-odd bispectrum

Extended analysis techniques to include parity-odd configurations

Abstract

Parity-odd non-Gaussianities create a variety of temperature bispectra in the cosmic microwave background (CMB), defined in the domain: $\ell_1 + \ell_2 + \ell_3 = {\rm odd}$. These models are yet unconstrained in the literature, that so far focused exclusively on the more common parity-even scenarios. In this work, we provide the first experimental constraints on parity-odd bispectrum signals in WMAP 9-year temperature data, using a separable modal parity-odd estimator. Comparing theoretical bispectrum templates to the observed bispectrum, we place constraints on the so-called nonlineality parameters of parity-odd tensor non-Gaussianities predicted by several Early Universe models. Our technique also generates a model-independent, smoothed reconstruction of the bispectrum of the data for parity-odd configurations.