T. M. C. Abbott, M. Aguena, A. Alarcon, O. Alves, A. Amon, F. Andrade-Oliveira, J. Annis, S. Avila, D. Bacon, E. J. Baxter, K. Bechtol, M. R. Becker, G. M. Bernstein, S. Birrer, J. Blazek, S. Bocquet, A. Brandao-Souza, S. L. Bridle, D. Brooks, D. L. Burke, H. Camacho, A. Campos, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, R. Cawthon, C. Chang, A. Chen, R. Chen, A. Choi, C. J. Conselice, J. P. Cordero, M. Costanzi, M. Crocce, L. N. da Costa, M. E. S. Pereira, C. Davis, T. M. Davis, J. DeRose, S. Desai, E. Di Valentino, H. T. Diehl, S. Dodelson, P. Doel, C. Doux, A. Drlica-Wagner, K. Eckert, T. F. Eifler, F. Elsner, J. Elvin-Poole, S. Everett, X. Fang, A. Farahi, I. Ferrero, A. Ferté, B. Flaugher, P. Fosalba, D. Friedel, O. Friedrich, J. A. Frieman, J. García-Bellido, M. Gatti, L. Giani, T. Giannantonio, G. Giannini, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, N. Hamaus, I. Harrison, W. G. Hartley, K. Herner, S. R. Hinton, D. L. Hollowood, K. Honscheid, H. Huang, E. M. Huff, D. Huterer, B. Jain, D. J. James, M. Jarvis, N. Jeffrey, T. E. Jeltema, A. Kovacs, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, S. Lee, P. -F. Leget, P. Lemos, C. D. Leonard, **A. R. Liddle**, M. Lima, H. Lin, N. MacCrann, J. L. Marshall, J. Mccullough, J. Mena-Fernández, F. Menanteau, R. Miquel, V. Miranda, J. J. Mohr, J. Muir, J. Myles, S. Nadathur, A. Navarro-Alsina, R. C. Nichol, R. L. C. Ogando, Y. Omori, A. Palmese, S. Pandey, Y. Park, M. Paterno, F. Paz-Chinchón, W. J. Percival, A. Pieres, A. A. Plazas Malagón, A. Porredon, J. Prat, M. Raveri, M. Rodriguez-Monroy, P. Rogozenski, R. P. Rollins, A. K. Romer, A. Roodman, R. Rosenfeld, A. J. Ross, E. S. Rykoff, S. Samuroff, C. Sánchez, E. Sanchez, J. Sanchez, D. Sanchez Cid, V. Scarpine, D. Scolnic, L. F. Secco, I. Sevilla-Noarbe, E. Sheldon, T. Shin, M. Smith, M. Soares-Santos, E. Suchyta, M. Tabbutt, G. Tarle, D. Thomas, C. To, A. Troja, M. A. Troxel, I. Tutusaus, T. N. Varga, M. Vincenzi, A. R. Walker, N. Weaverdyck, R. H. Wechsler, J. Weller, B. Yanny, B. Yin, Y. Zhang, J. Zuntz, DES Collaboration

**Abstract**

**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 two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. 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

**ΛCDM**extensions are dark energy with a time-dependent equation of state, nonzero spatial curvature, additional relativistic degrees of freedom, sterile neutrinos with eV-scale mass, modifications of gravitational physics, and a binned

*σ*

_{8}(

*z*) model which serves as a phenomenological probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find (

*w*

_{p},

*w*

_{a})=(−0.99

_{−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})=(−1.03

_{−0.03}

^{+0.04},−0.4

_{−0.3}

^{+0.4}) with

*z*

_{p}=0.21 for the combination of ll data considered. Curvature constraints of

*Ω*

_{k}=0.0009±0.0017 and effective elativistic species

*N*

_{eff}=3.10+0.15−0.16 are dominated by external data, though adding DES information to external low-redshift probes tightens the

*Ω*

_{k}constraints that can be made without cosmic microwave background bservables by 20%. For massive sterile neutrinos, DES combined with xternal ata improves the upper bound on the mass meff by a factor of 3 compared to revious analyses, giving 95% limits of (Δ

*N*

_{eff},

*m*

_{eff})≤(0.28,0.20 eV) when sing priors matching a comparable Planck analysis. For modified gravity, we onstrain changes to the lensing and Poisson equations controlled by unctions 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±0.05,0.08

_{−0.19}

^{+0.21}) for the combination of ll data, both at 68% confidence. Overall, we find no significant evidence for hysics beyond

**ΛCDM**.

**Keywords**

Cosmological constant; Cosmological parameters; Cosmology; Dark energy; Dark matter; Galaxies; Large scale structure of the Universe; Telescopes; Gravitation, Cosmology & Astrophysics

**Physical Review D**

Volume 107, Issue 8, Page 46

2023 April