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Published July 15, 2023 | Version Published
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Measurement of the CMB temperature power spectrum and constraints on cosmology from the SPT-3G 2018 TT, TE, and EE dataset

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Abstract

We present a sample-variance-limited measurement of the temperature power spectrum (TT) of the cosmic microwave background using observations of a ∼1500  deg² field made by the SPT-3G in 2018. We report multifrequency power spectrum measurements at 95, 150, and 220 GHz covering the angular multipole range 750 ≤ ℓ < 3000. We combine this TT measurement with the published polarization power spectrum measurements from the 2018 observing season and update their associated covariance matrix to complete the SPT-3G 2018 TT/TE/EE dataset. This is the first analysis to present cosmological constraints from SPT TT, TE, and EE power spectrum measurements jointly. We blind the cosmological results and subject the dataset to a series of consistency tests at the power spectrum and parameter level. We find excellent agreement between frequencies and spectrum types and our results are robust to the modeling of astrophysical foregrounds. We report results for ΛCDM and a series of extensions, drawing on the following parameters: the amplitude of the gravitational lensing effect on primary power spectra A_L, the effective number of neutrino species N_(eff), the primordial helium abundance Y_P, and the baryon clumping factor due to primordial magnetic fields b. We find that the SPT-3G 2018 TT/TE/EE data are well fit by ΛCDM with a probability to exceed of 15%. For ΛCDM, we constrain the expansion rate today to H₀ = 68.3 ± 1.5  km s⁻¹ Mpc⁻¹ and the combined structure growth parameter to S₈ = 0.797 ± 0.042. The SPT-based results are effectively independent of Planck, and the cosmological parameter constraints from either dataset are within <1σ of each other. The addition of temperature data to the SPT-3G TE/EE power spectra improves constraints by 8–27% for each of the ΛCDM cosmological parameters. When additionally fitting A_L, N_(eff), or N_(eff) + Y_P, the posteriors of these parameters tighten by 5–24%. In the case of primordial magnetic fields, complete TT/TE/EE power spectrum measurements are necessary to break the degeneracy between b and nₛ, the spectral index of primordial density perturbations. We report a 95% confidence upper limit from SPT-3G data of b < 1.0. The cosmological constraints in this work are the tightest from SPT primary power spectrum measurements to date and the analysis forms a new framework for future SPT analyses.

Copyright and License

© 2023 American Physical Society.

Acknowledgement

We thank Karsten Jedamzik and Levon Pogosian for their help with models featuring baryon clumping due to primordial magnetic fields. The South Pole Telescope program is supported by the National Science Foundation (NSF) through Awards No. OPP-1852617 and No. OPP-2147371. Partial support is also provided by the Kavli Institute of Cosmological Physics at the University of Chicago. Argonne National Laboratory's work was supported by the U.S. Department of Energy, Office of High Energy Physics, under Contract No. DE-AC02-06CH11357. Work at Fermi National Accelerator Laboratory, a DOE-OS, HEP User Facility managed by the Fermi Research Alliance, LLC, was supported under Contract No. DE-AC02-07CH11359. The Cardiff authors acknowledge support from the UK Science and Technologies Facilities Council (STFC). The IAP authors acknowledge support from the Centre National d'Études Spatiales (CNES). This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme (Grant Agreement No. 101001897). This research used resources of the IN2P3 Computer Center [70]. M. A. and J. V. acknowledge support from the Center for AstroPhysical Surveys at the National Center for Supercomputing Applications in Urbana, IL. J. V. acknowledges support from the Sloan Foundation. K. F. acknowledges support from the Department of Energy Office of Science Graduate Student Research (SCGSR) Program. The Melbourne authors acknowledge support from the Australian Research Council's Discovery Project scheme (Grant No. DP210102386). L. B. acknowledges support from the Albert Shimmins Fund. The McGill authors acknowledge funding from the Natural Sciences and Engineering Research Council of Canada, Canadian Institute for Advanced Research, and the Fonds de recherche du Québec Nature et technologies. The UCLA and MSU authors acknowledge support from Grants No. NSF AST-1716965 and No. CSSI-1835865. A. S. M. is supported by the Mullard Space Science Laboratory (MSSL) STFC Consolidated Grant. This research was done using resources provided by the Open Science Grid [71,72], which is supported by the NSF Award No. 1148698, and the U.S. Department of Energy's Office of Science. Some of the results in this paper have been derived using the healpy and healpix12 packages [73,74]. The data analysis pipeline also uses the scientific python stack [75–77].

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Additional details

Identifiers

ISSN
2470-0029

Funding

National Science Foundation
OPP-1852617
National Science Foundation
OPP-2147371
University of Chicago
United States Department of Energy
DE-AC02-06CH11357
United States Department of Energy
DE-AC02-07CH11359
Science and Technology Facilities Council
Centre National d'Études Spatiales
European Research Council
101001897
Institut National de Physique Nucléaire et de Physique des Particules
National Center for Supercomputing Applications
Alfred P. Sloan Foundation
Australian Research Council
DP210102386
Natural Sciences and Engineering Research Council
Canadian Institute for Advanced Research
Fonds de Recherche du Québec – Nature et Technologies
National Science Foundation
AST-1716965
National Science Foundation
OAC-1835865
University of Chicago
National Science Foundation
PHY-1148698