A novel approach to reconstructing signals of isotropy violation from a masked CMB sky

TL;DR

This paper introduces a new bipolar spherical harmonic method to reconstruct signals of isotropy violation in masked CMB data, effectively addressing biases caused by masking and enabling detection of SI violations like Doppler boost.

Contribution

The paper presents a novel semi-analytical bipolar spherical harmonic approach to analyze isotropy violations in masked CMB skies, improving bias handling and detection capabilities.

Findings

Successfully recovered Doppler boost signals from simulated masked CMB skies.

The method effectively accounts for mask-induced biases in SI violation analysis.

Demonstrated the general applicability of the approach to arbitrary SI violations.

Abstract

Statistical isotropy (SI) is one of the fundamental assumptions made in cosmological model building. This assumption is now being rigorously tested using the almost full sky measurements of the CMB anisotropies. A major hurdle in any such analysis is to handle the large biases induced due to the process of masking. We have developed a new method of analysis, using the bipolar spherical harmonic basis functions, in which we semi-analytically evaluate the modifications to SI violation induced by the mask. The method developed here is generic and can be potentially used to search for any arbitrary form of SI violation. We specifically demonstrate the working of this method by recovering the Doppler boost signal from a set of simulated, masked CMB skies.