QUBIC II: Spectral polarimetry with bolometric interferometry

Bolometric interferometry is a novel technique that has the ability to perform spectral imaging. A bolometric interferometer observes the sky in a wide frequency band and can reconstruct sky maps in several sub-bands within the physical band in post-processing of the data. This provides a powerful spectral method to discriminate between the cosmic mi-crowave background (CMB) and astrophysical foregrounds. In this paper, the methodology is illustrated with examples based on the Q & U Bolometric Interferometer for Cosmology (QUBIC) which is a ground-based instrument designed to measure the B-mo de polarization of the sky at millimeter wavelengths. We consider the specific cases of point source reconstruc-tion and Galactic dust mapping and we characterize the point spread function as a function of frequency. We study the noise properties of spectral imaging, especially the correlations between sub-bands, using end-to-end simulations together with a fast noise simulator. We conclude showing that spectral imaging performance are nearly optimal up to five sub-bands in the case of QUBIC.

Automated summary

Bolometric interferometry is a novel technique for spectral imaging, which can differentiate between the cosmic microwave background and astrophysical foregrounds. This paper illustrates the methodology using QUBIC and investigates point source reconstruction and Galactic dust mapping, as well as the noise properties of spectral imaging.