Optimal cosmic microwave background map-making in the presence of cross-correlated noise

TL;DR

This paper extends the ROMA map-making algorithm to include cross-correlated noise among detectors, improving the accuracy of CMB polarization maps and reducing error bars in power spectrum estimates, which is vital for B-mode polarization studies.

Contribution

The paper introduces a generalized ROMA algorithm that accounts for cross-correlated noise in CMB experiments, enhancing map accuracy and power spectrum estimation.

Findings

Inclusion of cross-correlated noise reduces power spectrum error bars.

The extended algorithm provides more realistic estimates of CMB polarization.

Application to LSPE shows significant improvement in measurement precision.

Abstract

We present an extension of the ROMA map-making algorithm for the generation of optimal cosmic microwave background polarization maps. The new code allows for a possible cross-correlated noise component among the detectors of a CMB experiment. A promising application is the forthcoming LSPE balloon-borne experiment, which is devoted to the accurate observation of CMB polarization at large angular scales. We generalized the noise covariance matrix in time domain to account for all the off-diagonal terms due to the detector cross-talk. Hence, we performed preliminary forecasts of the LSPE-SWIPE instrument. We found that considering the noise cross-correlation among the detectors results in a more realistic estimate of the angular power spectra. In particular, the extended ROMA algorithm has provided a considerable reduction of the spectra error bars. We expect that this improvement could be crucial in constraining the B-mode polarization at the largest scales.