Spectral Imaging with QUBIC: building astrophysical components from Time-Ordered-Data using Bolometric Interferometry

TL;DR

This paper presents a novel component separation method during map-making for CMB polarization data, improving the accuracy of B-mode detection and reducing biases in cosmological analysis, specifically applied to QUBIC data.

Contribution

The paper introduces a new technique that performs component separation in the time domain during map-making, incorporating astrophysical foregrounds and systematics, and demonstrates its effectiveness with a software pipeline.

Findings

Method achieves $\sigma(r) o 0.023$ with simulated QUBIC data.

Allows joint analysis of multiple experiments for enhanced precision.

Reduces biases in cosmological parameter estimation.

Abstract

The detection of B-modes in the CMB polarization pattern is a major issue in modern cosmology and must therefore be handled with analytical methods that produce reliable results. We describe a method that uses the frequency dependency of the QUBIC synthesized beam to perform component separation at the map-making stage, to obtain more precise results. We aim to demonstrate the feasibility of component separation during the map-making stage in time domain space. This new technique leads to a more accurate description of the data and reduces the biases in cosmological analysis. The method uses a library for highly parallel computation which facilitates the programming and permits the description of experiments as easily manipulated operators. These operators can be combined to obtain a joint analysis using several experiments leading to maximized precision. The results show that the method works well and permits end-to-end analysis for the CMB experiments, and in particular, for QUBIC. The method includes astrophysical foregrounds, and also systematic effects like gain variation in the detectors. We developed a software pipeline that produces uncertainties on tensor-to-scalar ratio at the level of $\sigma(r) \sim 0.023$ using only QUBIC simulated data.