CMB lensing power spectrum with next generation surveys

TL;DR

This paper presents a new iterative estimator for the CMB lensing power spectrum that improves constraints, remains unbiased, and is computationally efficient, enhancing the analysis of future survey data.

Contribution

The paper introduces a novel iterative lensing spectrum estimator that outperforms the quadratic estimator in constraining power while maintaining robustness and computational feasibility.

Findings

Doubles constraints on lensing amplitude.

Unbiased estimator independent of noise and cosmology assumptions.

Maintains computational efficiency comparable to quadratic estimator.

Abstract

We introduce a new estimator of the CMB lensing power spectrum, together with its likelihood, based on iterative lensing reconstruction. Despite the increased complexity of the lensing maps, this estimator shares similarities with the standard quadratic estimator. Most importantly, it is unbiased towards the assumptions done on the noise and cosmology for the lensing reconstruction. This new spectrum estimator can double the constraints on the lensing amplitude compared to the quadratic estimator, while keeping numerical cost under control and being robust to errors.