Forecasts of CMB lensing reconstruction of AliCPT-1 from the foreground cleaned polarization data

TL;DR

This paper demonstrates the feasibility of CMB lensing reconstruction with AliCPT-1 after foreground removal, combining multiple frequency bands and advanced cleaning methods, achieving a signal-to-noise ratio comparable to other stage-III telescopes.

Contribution

It introduces a combined foreground cleaning approach using NILC and cILC methods for AliCPT-1 polarization data, enabling effective lensing reconstruction.

Findings

Effective residual noise in E- and B-maps is approximately 15 and 25 μK·arcmin.

CMB lensing reconstruction SNR is about 4.5 with the proposed methods.

AliCPT-1's lensing reconstruction capability is comparable to other stage-III telescopes.

Abstract

Cosmic microwave background radiation (CMB) observations are unavoidably contaminated by emission from various extra-galactic foregrounds, which must be removed to obtain reliable measurements of the cosmological signal. In this paper, we demonstrate CMB lensing reconstruction in AliCPT-1 after foreground removal, combine the two bands of AliCPT-1 (90 and 150~GHz) with Planck HFI bands (100, 143, 217 and 353~GHz) and with the WMAP-K band (23~GHz). In order to balance contamination by instrumental noise and foreground residual bias, we adopt the Needlet Internal Linear Combination (NILC) method to clean the E-map and the constrained Internal Linear Combination (cILC) method to clean the B-map. The latter utilizes additional constraints on average frequency scaling of the dust and synchrotron to remove foregrounds at the expense of somewhat noisier maps. Assuming 4 modules observing 1 season from simulation data, the resulting effective residual noise in E- and B-map are roughly $15~\mu{\rm K}\cdot{\rm arcmin}$ and $25~\mu{\rm K}\cdot{\rm arcmin}$, respectively. As a result, the CMB lensing reconstruction signal-to-noise ratio (SNR) from polarization data is about SNR$\,\approx\,$4.5. This lensing reconstruction capability is comparable to that of other stage-III small aperture millimeter CMB telescopes.