Dark Energy Survey Year 3 results: Constraints on extensions to Λ CDM with weak lensing and galaxy clustering
Abstract
We constrain six possible extensions to the Λ cold dark matter (CDM) model using measurements from the Dark Energy Survey's first three years of observations, alone and in combination with external cosmological probes. The DES data are the twopoint correlation functions of weak gravitational lensing, galaxy clustering, and their crosscorrelation. We use simulated data vectors and blind analyses of real data to validate the robustness of our results to astrophysical and modeling systematic errors. In many cases, constraining power is limited by the absence of theoretical predictions beyond the linear regime that are reliable at our required precision. The Λ CDM extensions are dark energy with a timedependent equation of state, nonzero spatial curvature, additional relativistic degrees of freedom, sterile neutrinos with eVscale mass, modifications of gravitational physics, and a binned σ_{8}(z ) model which serves as a phenomenological probe of structure growth. For the timevarying dark energy equation of state evaluated at the pivot redshift we find (w_{p},w_{a})=(0.9 9_{0.17}^{+0.28},0.9 ±1.2 ) at 68% confidence with z_{p}=0.24 from the DES measurements alone, and (w_{p},w_{a})=(1.0 3_{0.03}^{+0.04},0. 4_{0.3}^{+0.4}) with z_{p}=0.21 for the combination of all data considered. Curvature constraints of Ω_{k}=0.0009 ±0.0017 and effective relativistic species N_{eff}=3.1 0_{0.16}^{+0.15} are dominated by external data, though adding DES information to external lowredshift probes tightens the Ω_{k} constraints that can be made without cosmic microwave background observables by 20%. For massive sterile neutrinos, DES combined with external data improves the upper bound on the mass m_{eff} by a factor of 3 compared to previous analyses, giving 95% limits of (Δ N_{eff},m_{eff})≤(0.28 ,0.20 eV ) when using priors matching a comparable Planck analysis. For modified gravity, we constrain changes to the lensing and Poisson equations controlled by functions Σ (k ,z )=Σ_{0}Ω_{Λ}(z )/Ω_{Λ ,0} and μ (k ,z )=μ_{0}Ω_{Λ}(z )/Ω_{Λ ,0}, respectively, to Σ_{0}=0. 6_{0.5}^{+0.4} from DES alone and (Σ_{0},μ_{0})=(0.04 ±0.05 ,0.0 8_{0.19}^{+0.21}) for the combination of all data, both at 68% confidence. Overall, we find no significant evidence for physics beyond Λ CDM .
 Publication:

Physical Review D
 Pub Date:
 April 2023
 DOI:
 10.1103/PhysRevD.107.083504
 arXiv:
 arXiv:2207.05766
 Bibcode:
 2023PhRvD.107h3504A
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 Updated to match published version and fix a citation reference. 46 pages, 25 figures, data available at https://dev.des.ncsa.illinois.edu/releases/y3a2/Y3keyextensions