Forecasting ground-based sensitivity to the Rayleigh scattering of the CMB in the presence of astrophysical foregrounds

• Published in: Physical review. D 2022-09, Vol.106 (6), Article 063502
• Main Authors: Dibert, Karia R., Anderson, Adam J., Bender, Amy N., Benson, Bradford A., Bianchini, Federico, Carlstrom, John E., Crawford, Thomas M., Gualtieri, Riccardo, Omori, Yuuki, Pan, Zhaodi, Raghunathan, Srinivasan, Reichardt, Christian L., Wu, W. L. Kimmy
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; cosmic microwave background; telescopes
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.106.063502

The Rayleigh scattering of cosmic microwave background (CMB) photons off the neutral hydrogen produced during recombination effectively creates an additional scattering surface after recombination that encodes new cosmological information, including the expansion and ionization history of the universe. A first detection of Rayleigh scattering is a tantalizing target for next-generation CMB experiments. We have developed a Rayleigh scattering forecasting pipeline that includes instrumental effects, atmospheric noise, and astrophysical foregrounds (e.g., Galactic dust, cosmic infrared background, or CIB, and the thermal Sunyaev-Zel'dovich effect). We forecast the Rayleigh scattering detection significance for several upcoming ground -based experiments, including SPT-3G+, Simons Observatory, CCAT-prime, and CMB-S4, and examine the limitations from atmospheric and astrophysical foregrounds as well as potential mitigation strategies. When combined with Planck data, here we estimate that the ground-based experiments will detect Rayleigh scattering with a significance between 1.6 and 3.7, primarily limited by atmospheric noise and the CIB.