Astro2020 APC White Paper: The need for better tools to design future CMB experiments

TL;DR

This paper emphasizes the need for advanced tools to simulate and analyze future CMB experiments, addressing challenges like foregrounds and systematics to improve the detection of primordial gravitational waves.

Contribution

It advocates for developing robust simulation tools to better design and assess future CMB experiments targeting very low tensor-to-scalar ratios.

Findings

Current tools are insufficient for next-generation experiment design

Enhanced simulation capabilities can support space mission planning at r ~ 10^{-4}

Ground-based experiments would also benefit from improved analysis tools

Abstract

This white paper addresses key challenges for the design of next-decade Cosmic Microwave Background (CMB) experiments, and for assessing their capability to extract cosmological information from CMB polarization. We focus here on the challenges posed by foreground emission, CMB lensing, and instrumental systematics to detect the signal that arises from gravitational waves sourced by inflation and parameterized by $r$, at the level of $r \sim 10^{-3}$ or lower, as proposed for future observational efforts. We argue that more accurate and robust analysis and simulation tools are required for these experiments to realize their promise. We are optimistic that the capability to simulate the joint impact of foregrounds, CMB lensing, and systematics can be developed to the level necessary to support the design of a space mission at $r \sim 10^{-4}$ in a few years. We make the case here for supporting such work. Although ground-based efforts present additional challenges (e.g., atmosphere, ground pickup), which are not addressed here, they would also benefit from these improved simulation capabilities.