The Simons Observatory: Combining delensing and foreground cleaning for improved constraints on inflation

• DOI: 10.48550/arxiv.2405.13201
• Publication Date: 2024-01-01
• Authors: Hertig, Emilie; Wolz, Kevin; Namikawa, Toshiya; Lizancos, Antón B...; Azzoni, Susanna; Challinor, Anthony
• Keywords: Cosmology and Nongalactic Astrophysics (astro-ph.CO); FOS: Physical sciences; Astrophysics - Cosmology and Nongalactic Astrophysics

4 pages, 4 figures. Contribution to the 2024 Cosmology session of the 58th Rencontres de Moriond<br/>The Simons Observatory (SO), a next-generation ground-based CMB experiment in its final stages of construction, will target primordial $B$-modes with unprecedented sensitivity to set tight bounds on the amplitude of inflationary gravitational waves. Aiming to infer the tensor-to-scalar ratio $r$ with precision $σ(r=0) \leq 0.003$, SO will rely on powerful component-separation algorithms to distinguish the faint primordial signal from stronger sources of large-scale $B$-modes such as Galactic foregrounds and weak gravitational lensing. We present an analysis pipeline that performs delensing and foreground cleaning simultaneously by including multifrequency CMB data and a lensing $B$-mode template in a power-spectrum-based likelihood. Here, we demonstrate this algorithm on masked SO-like simulations containing inhomogeneous noise and non-Gaussian foregrounds. The lensing convergence is reconstructed from high-resolution simulations of the CMB and external mass tracers. Using optimized pixel weights for power spectrum estimation, the target precision for SO's nominal design is achieved and delensing reduces $σ(r)$ by 27-37%, depending on foreground complexity.<br/>