QUBIC I: Overview and ScienceProgram

TL;DR

QUBIC is a novel bolometric interferometer designed to measure the CMB B-mode polarization, combining interferometry and bolometric detectors to improve control of systematics and foreground removal, aiming for high sensitivity in primordial gravitational wave detection.

Contribution

This paper introduces the QUBIC instrument, highlighting its innovative design that merges interferometry with bolometric detectors for improved CMB polarization measurements.

Findings

QUBIC can produce multi-band CMB polarization maps.

Calibration results validate the instrument's performance.

Forecasts indicate a sensitivity of σ(r)=0.015 for tensor-to-scalar ratio after three years.

Abstract

The Q $\&$ U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized for the measurement of the B-mode polarization of the Cosmic Microwave Background (CMB), which is one of the major challenges of observational cosmology. The signal is expected to be of the order of a few tens of nK, prone to instrumental systematic effects and polluted by various astrophysical foregrounds which can only be controlled through multichroic observations. QUBIC is designed to address these observational issues with a novel approach that combines the advantages of interferometry in terms of control of instrumental systematic effects with those of bolometric detectors in terms of wide-band, background-limited sensitivity. The QUBIC synthesized beam has a frequency-dependent shape that results in the ability to produce maps of the CMB polarization in multiple sub-bands within the two physical bands of the instrument (150 and 220 GHz). These features make QUBIC complementary to other instruments and makes it particularly well suited to characterize and remove Galactic foreground contamination. In this article, first of a series of eight, we give an overview of the QUBIC instrument design, the main results of the calibration campaign, and present the scientific program of QUBIC including not only the measurement of primordial B-modes, but also the measurement of Galactic foregrounds. We give forecasts for typical observations and measurements: with three years of integration on the sky and assuming perfect foreground removal as well as stable atmospheric conditions from our site in Argentina, our simulations show that we can achieve a statistical sensitivity to the effective tensor-to-scalar ratio (including primordial and foreground B-modes) $\sigma(r)=0.015$.