http://arxiv.org/abs/2112.14008
We address a current caveat in the deconvolution of the Primordial Power Spectrum (PPS), from observed Cosmic Microwave Background (CMB) temperature anisotropy, in the presence of weak lensing of the CMB by the large scale structure (LSS) in the Universe. We propose a modification to the popular Richardson-Lucy (RL) deconvolution algorithm used in the context of reconstructing a free-form PPS, $P_R(k)$ from observed lensed CMB temperature anisotropy power spectrum $\widetilde{C}_{\ell}^{TT}$. We show that the modified RL algorithm works in the context of a non-linear convolution problem, such as in the case of weak lensing. The Non-Linear Iterative Richardson-Lucy (NIRL) algorithm is successful at both convergence, as well as fidelity, in reconstructing features in some underlying PPS. This makes PPS reconstruction efforts more robust in the context of lensed CMB temperature observations. No prior assumptions on the PPS are involved during the iterative delensing process, and distinct improvement is noted over a power-law template based delensing approach used earlier, at the cost of moderately increased computational cost due to the NIRL reconstruction.
R. Chandra and T. Souradeep
Thu, 30 Dec 21
3/71
Comments: 20 pages, 8 Figures (with subfigures), 6 Tables