SPT-3G D1: cosmological constraints on ΛCDM extensions and consistency with DESI DR2 baryon acoustic oscillations

ORAL

Abstract

The SPT-3G camera on the South Pole Telescope observes CMB anisotropies at high precision and arcminute resolution, enabling powerful tests of the ΛCDM model and possible extensions. I will present constraints on these extended models from the SPT-3G D1 data release, which uses data from the 2019-2020 observations with the SPT-3G camera over 4% of the southern sky. SPT-3G D1 data, combined with CMB data from Planck and ACT, shows no preference for evolving dark energy, new light particles, modified recombination, or an excess lensing amplitude. However, when combined with baryon acoustic oscillation measurements from DESI DR2, we find a 2.8 σ difference within ΛCDM. I will discuss how this difference projects as a 2–3 σ preference for some of these extended models when CMB and DESI BAO data are analyzed jointly.

*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 Kavili Institute for Cosmological Physics at the University of Chicago and European Research Council. Additional support came from the Michael and Ester Vaida Endowed Chair in Cosmology and Astrophysics at UC Davis.

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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

  • Gabriel P Lynch

    • University of California, Davis

Authors

  • Gabriel P Lynch

    • University of California, Davis

  • 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

  • Yuuki Omori

    • University of Chicago

  • Cynthis S Trendafilova

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