Elbers, W;
Aviles, A;
Noriega, HE;
Chebat, D;
Menegas, A;
Frenk, CS;
Garcia-Quintero, C;
... Lahav, O; + view all
(2025)
Constraints on neutrino physics from DESI DR2 BAO and DR1 full shape.
Physical Review D
, 112
, Article 083513. 10.1103/w9pk-xsk7.
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Abstract
The Dark Energy Spectroscopic Instrument (DESI) Collaboration has obtained robust measurements of baryon acoustic oscillations in the redshift range 0.1 < z < 4.2, based on the Lyman-α forest and galaxies from data release 2. We combine these measurements with cosmic microwave background (CMB) data from Planck and the Atacama Cosmology Telescope to place our tightest constraints yet on the sum of neutrino masses. Assuming the cosmological ΛCDM model and three degenerate neutrino states, we find Σmν < 0.0642 eV (95%) with a marginalized error of σ(Σmν) = 0.020 eV. We also constrain the effective number of neutrino species, finding Neff = 3.23 +0.35/-0.34 (95%), in line with the Standard Model prediction. When accounting for neutrino oscillation constraints, we find a preference for the normal mass ordering and an upper limit on the lightest neutrino mass of ml < 0.023 eV (95%). However, we determine using frequentist and Bayesian methods that our constraints are in tension with the lower limits derived from neutrino oscillations. Correcting for the physical boundary at zero mass, we report a 95% Feldman-Cousins upper limit of Σmν < 0.053 eV, breaching the lower limit from neutrino oscillations. Considering a more general Bayesian analysis with an effective cosmological neutrino mass parameter, Σmν,eff, that allows for negative energy densities and removes unsatisfactory prior weight effects, we derive constraints that are in 3σ tension with the same oscillation limit, while the error rises to σ(Σmν,eff) = 0.053 eV. In the absence of unknown systematics, this finding could be interpreted as a hint of new physics not necessarily related to neutrinos. The preference of DESI and CMB data for an evolving dark energy model offers one possible solution. In the w0waCDM model, we find Σmν < 0.163 eV (95%), relaxing the neutrino tension. These constraints all rely on the effects of neutrinos on the cosmic expansion history. Using full-shape power spectrum measurements of data release 1 galaxies, we place complementary constraints that rely on neutrino free streaming. Our strongest such limit in ΛCDM, using selected CMB priors, is Σmν < 0.193 eV (95%).
| Type: | Article |
|---|---|
| Title: | Constraints on neutrino physics from DESI DR2 BAO and DR1 full shape |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/w9pk-xsk7 |
| Publisher version: | https://doi.org/10.1103/w9pk-xsk7 |
| Language: | English |
| Additional information: | Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. https://creativecommons.org/licenses/by/4.0/ Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. |
| Keywords: | Baryon acoustic oscillations, Cosmic microwave background, Dark energy, Large scale structure of the Universe, Neutrino mass |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10218134 |
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