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Relaxing DESI DR2 BAO Constraints on $\sum m_ν$ with Planck and SPT-3G 2018 in the Context of SPT D1

Dmitry Gorbunov, Nikita Nedelko

TL;DR

This paper investigates how the inferred sum of active neutrino masses $\sum m_ν$ depends on the chosen CMB baseline by comparing two SPT-3G–Planck datasets. The authors construct a CMB baseline from SPT-3G 2018 data and, separately, a CMB-D1 baseline using the 2019–2020 SPT-3G data, both combined with Planck lensing and DESI DR2 BAO along with DES Y1 and Pantheon+ constraints, analyzed in a ΛCDM+{\sum m_ν} framework with three degenerate neutrino masses. They find that the 2018 baseline yields $\sum m_ν<0.11$ eV when DESI DR2 BAO is included (and $<0.138$ eV with DES Y1 and Pantheon+), while the 2019–2020 D1 baseline tightens the bound to $<0.082$ eV with the posterior peaking near zero. This pronounced shift underscores pipeline- and data-version dependence in cosmological neutrino-mass inferences and motivates reanalysis of older datasets with updated pipelines to resolve tensions between DESI, Planck, and oscillation lower bounds.

Abstract

We present constraints on the sum of neutrino masses $\sum m_ν$ from a dataset incorporating the full SPT-3G 2018 TT/TE/EE+lensing spectra together with Planck PR4 lensing and low-$\ell$ parts of the Planck PR3 spectra. Using it as a baseline for the DESI DR2 BAO measurements, we arrive at a $95\%$ upper limit of $\sum m_ν< 0.11$ eV, relaxing the tension between $\rm Λ$CDM and lower bounds on $\sum m_ν$ based on neutrino oscillation experiments. When including DES Y1 weak lensing information and the Pantheon+ SNIa catalog, the limit is further loosened to $\sum m_ν<0.138$ eV with a slight preference for $\sum m_ν>0$. On contrast, replacing SPT-3G 2018 primary CMB and lensing spectra with ones from the SPT-3G 2019-2020 (D1) release tightens the overall constraint to $<0.082$ eV and pushes the $\sum m_ν$ posterior mode value to zero, indicating a preference for quasi-negative neutrino masses in line with the D1 analysis. This is a curious shift within SPT-3G measurements of the same field taken in 2018 and in 2019-2020 and processed with different analysis pipelines.

Relaxing DESI DR2 BAO Constraints on $\sum m_ν$ with Planck and SPT-3G 2018 in the Context of SPT D1

TL;DR

This paper investigates how the inferred sum of active neutrino masses depends on the chosen CMB baseline by comparing two SPT-3G–Planck datasets. The authors construct a CMB baseline from SPT-3G 2018 data and, separately, a CMB-D1 baseline using the 2019–2020 SPT-3G data, both combined with Planck lensing and DESI DR2 BAO along with DES Y1 and Pantheon+ constraints, analyzed in a ΛCDM+{\sum m_ν} framework with three degenerate neutrino masses. They find that the 2018 baseline yields eV when DESI DR2 BAO is included (and eV with DES Y1 and Pantheon+), while the 2019–2020 D1 baseline tightens the bound to eV with the posterior peaking near zero. This pronounced shift underscores pipeline- and data-version dependence in cosmological neutrino-mass inferences and motivates reanalysis of older datasets with updated pipelines to resolve tensions between DESI, Planck, and oscillation lower bounds.

Abstract

We present constraints on the sum of neutrino masses from a dataset incorporating the full SPT-3G 2018 TT/TE/EE+lensing spectra together with Planck PR4 lensing and low- parts of the Planck PR3 spectra. Using it as a baseline for the DESI DR2 BAO measurements, we arrive at a upper limit of eV, relaxing the tension between CDM and lower bounds on based on neutrino oscillation experiments. When including DES Y1 weak lensing information and the Pantheon+ SNIa catalog, the limit is further loosened to eV with a slight preference for . On contrast, replacing SPT-3G 2018 primary CMB and lensing spectra with ones from the SPT-3G 2019-2020 (D1) release tightens the overall constraint to eV and pushes the posterior mode value to zero, indicating a preference for quasi-negative neutrino masses in line with the D1 analysis. This is a curious shift within SPT-3G measurements of the same field taken in 2018 and in 2019-2020 and processed with different analysis pipelines.
Paper Structure (6 sections, 1 figure, 4 tables)

This paper contains 6 sections, 1 figure, 4 tables.

Table of Contents

  1. Introduction
  2. The pipeline
  3. $\Lambda$CDM constraints
  4. Constraints on neutrino masses $\sum m_\nu$ with SPT-3G 2018
  5. Comparison to SPT-3G 2019-2020
  6. Discussion and Conclusions

Figures (1)

  • Figure 1: Marginalized 1D posterior distributions (normalized to the unit integral) of $\sum m_\nu$ (in $\,\text{eV}$) for datasets based on CMB (upper plot) and CMB-D1 (lower plot), with dashed vertical lines marking $95\%$ CL upper limits. Light green shading represents the $95\%$ CL limit from Planck PR4. Dark green shading represents the $95\%$ CL from the DESI DR2 "CMB+BAO" combination.