CMB lensing power spectrum estimation without instrument noise bias

作     者：Madhavacheril, Mathew S. Smith, Kendrick M. Sherwin, Blake D. Naess, Sigurd 

作者机构：Perimeter Institute for Theoretical Physics 31 Caroline Street N WaterlooONN2L 2Y5 Canada Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom Kavli Institute for Cosmology University of Cambridge CambridgeCB3 0HA United Kingdom Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2020年

核心收录：

主　　题：Power spectrum 

摘      要：The power spectrum of cosmic microwave background (CMB) lensing will be measured to sub-percent precision with upcoming surveys, enabling tight constraints on the sum of neutrino masses and other cosmological parameters. Measuring the lensing power spectrum involves the estimation of the connected trispectrum of the four-point function of the CMB map, which requires the subtraction of a large Gaussian disconnected noise bias. This reconstruction noise bias receives contributions both from CMB and foreground fluctuations as well as instrument noise (both detector and atmospheric noise for ground-based surveys). The debiasing procedure therefore relies on the quality of simulations of the instrument noise which may be expensive or inaccurate. We propose a new estimator that makes use of at least four splits of the CMB maps with independent instrument noise. This estimator makes the CMB lensing power spectrum completely insensitive to any assumptions made in modeling or simulating the instrument noise. We show that this estimator, in many practical situations, leads to no substantial loss in signal-to-noise. We provide an efficient algorithm for its computation that scales with the number of splits m as O(m2) as opposed to a naive O(m4) expectation. Copyright © 2020, The Authors. All rights reserved.