SPT-3G D1: CMB power spectra and constraints on ΛCDM parameters

ORAL

Abstract

I present measurements of the lensed CMB TT/TE/EE power spectra and constraints on ΛCDM parameters using a dataset acquired with the SPT-3G camera on the South Pole Telescope (SPT). The dataset, SPT-3G D1, comprises observations of 4% of the sky taken during the 2019 and 2020 austral winter observing seasons. The measurements of the EE (TE) spectra are the most precise to date at multipoles between 1800 (2200) and 4000. The spectra are fit well by ΛCDM. Our determination of the Hubble constant is 66.60 ± 0.60 km·s-1Mpc-1, 6.2 σ away from local measurements by SH0ES. The constraints on the ΛCDM parameters from SPT are consistent with those from the satellite experiment Planck and ground-based experiment Atacama Cosmology Telescope (ACT). The combined constraints from SPT and ACT are now comparable to those from Planck, which signals a turning point in CMB cosmology, where ground-based experiments will drive parameter constraints in coming years.

*The South Pole Telescope program is supported by the National Science Foundation Office of Polar Programs and the U.S. Department of Energy's Office of Science High Energy Physics. Additionally, this work is supported by organizations including the Kavli Institute for Cosmological Physics at the University of Chicago and European Research Council.

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Publication: Camphuis et al., "SPT-3G D1: CMB temperature and polarization power spectra and cosmology from 2019 and 2020 observations of the SPT-3G Main field", PRD, submitted, arXiv:2506.20707;
Khalife et al., "SPT-3G D1: Axion Early Dark Energy with CMB experiments and DESI", PRD, submitted, arXiv:2507.23355;
Ge et al., "Cosmology From CMB Lensing and Delensed EE Power Spectra Using 2019-2020 SPT-3G Polarization Data", PRD 111 (2025) 083534, arXiv:2411.06000;
Quan et al., "SPT-3G D1: Maps of the millimeter-wave sky from 2019 and 2020 observations of the SPT-3G Main field, in prep. as of Oct 2025

Presenters

  • Wei Quan

    • Argonne National Laboratory / University of Chicago

Authors

  • Etienne Camphuis

    • Institute of Astrophysics in Paris

  • Wei Quan

    • Argonne National Laboratory / University of Chicago

  • Lennart Balkenhol

    • Institute of Astrophysics in Paris

  • Ali Rida Khalife

    • Institute of Astrophysics in Paris

  • Fei Ge

    • University of California, Davis / California Institute of Technology

  • Federica Guidi

    • Institute of Astrophysics in Paris

  • Nicholas Huang

    • University of California, Berkeley

  • Gabriel Lynch

    • University of California, Davis

  • Yuuki Omori

    • University of Chicago

  • Cynthis S Trendafilova

    • University of Texas at Austin
    • Center for AstroPhysical Surveys, National Center for Supercomputing Applications