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

TL;DR

This paper combines multiple CMB and large-scale structure datasets to constrain the sum of neutrino masses, showing how different data releases and analysis choices impact the upper limits and inferred neutrino mass preferences.

Contribution

It provides updated neutrino mass constraints using SPT-3G 2018 and 2019-2020 data, highlighting the effects of data release versions and analysis pipelines on results.

Findings

Upper limit on neutrino mass is relaxed to 0.11 eV with baseline data.

Including additional datasets further loosens the constraint to 0.138 eV.

Replacing SPT-3G 2018 data with 2019-2020 data tightens the constraint to 0.082 eV and favors zero neutrino mass.

Abstract

We present constraints on the sum of neutrino masses $\sum m_\nu$ 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 $\sum m_\nu < 0.11$ eV, relaxing the tension between $\rm \Lambda$CDM and lower bounds on $\sum m_\nu$ based on neutrino oscillation experiments. When including DES Y1 weak lensing information and the Pantheon+ SNIa catalog, the limit is further loosened to $\sum m_\nu<0.138$ eV with a slight preference for $\sum m_\nu>0$. 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 $\sum m_\nu$ 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.