Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensing

Abstract

We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321 deg 2 of griz imaging data from the first year of the Dark Energy Survey (DES Y1). We combine three two-point functions: (i) the cosmic shear correlation function of 26 million source galaxies in four redshift bins, (ii) the galaxy angular autocorrelation function of 650,000 luminous red galaxies in five redshift bins, and (iii) the galaxy-shear cross-correlation of luminous red galaxy positions and source galaxy shears. To demonstrate the robustness of these results, we use independent pairs of galaxy shape, photometric-redshift estimation and validation, and likelihood analysis pipelines. To prevent confirmation bias, the bulk of the analysis was carried out while "blind" to the true results; we describe an extensive suite of systematics checks performed and passed during this blinded phase. The data are modeled in flat ΛCDM and wCDM cosmologies, marginalizing over 20 nuisance parameters, varying 6 (for ΛCDM) or 7 (for wCDM) cosmological parameters including the neutrino mass density and including the 457 × 457 element analytic covariance matrix. We find consistent cosmological results from these three two-point functions and from their combination obtain S 8 ≡ σ 8 ðΩ m =0.3Þ 0.5 ¼ 0.773 þ0.026 −0.020 and Ω m ¼ 0.267 þ0.030 −0.017 for ΛCDM; for wCDM, we find S 8 ¼ 0.782 þ0.036 −0.024 , Ω m ¼ 0.284 þ0.033 −0.030 , and w ¼ −0.82 þ0.21 −0.20 at 68% C.L. The precision of these DES Y1 constraints rivals that from the Planck cosmic microwave background measurements, allowing a comparison of structure in the very early and late Universe on equal terms. Although the DES Y1 best-fit values for S 8 and Ω m are lower than the central values from Planck for both ΛCDM and wCDM, the Bayes factor indicates that the DES Y1 and Planck data sets are consistent with each other in the context of ΛCDM. Combining DES Y1 with Planck, baryonic acoustic oscillation measurements from SDSS, 6dF, and BOSS and type Ia supernovae from the Joint Lightcurve Analysis data set, we derive very tight constraints on cosmological parameters: S 8 ¼ 0.802 AE 0.012 and Ω m ¼ 0.298 AE 0.007 in ΛCDM and w ¼ −1.00 þ0.05 −0.04 in wCDM. Upcoming Dark Energy Survey analyses will provide more stringent tests of the ΛCDM model and extensions such as a time-varying equation of state of dark energy or modified gravity.

Dark Energy Survey Hits a Triple

“…The Dark Energy Survey (DES) Collaboration demonstrates this idea by using three statistical measurements of galaxies to pin down values for the dark matter density, the cosmic expansion rate, and other parameters in cosmology. The collaboration has now released three years' worth of data, which covers an area of sky three times larger than their previous release [1]. The new analysis supports the standard cosmological model, with the measurements having unprecedented precision.…”

Non-standard neutrino cosmology dilutes the lensing anomaly

“…Future CMB measurements will have superb precision, and they could discriminate between neutrino interactions and uniformly enhanced lensing [55,57]. Furthermore, current surveys are rapidly improving our precision of the matter power spectrum [10,80], to the extent that they could start being sensitive to effects induced by neutrino self-interactions [27]. The light new scalar responsible for the long-range interaction could also give rise to observable departures from standard cosmology [36][37][38][39][40][41].…”

“…The standard cosmological model, remarkably simple but with profound implications, remains strikingly successful in many diverse environments [1][2][3][4][5][6][7][8][9][10][11]. The precision is such, that self-consistency tests are feasible and accurate.…”

An exploration of an early gravity transition in light of cosmological tensions

“…This was soon confirmed by the WMAP CMB observations (Bennett et al 2003;Spergel et al 2003), which showed that the dark energy comprises ∼ 70% of the mass-energy budget of the flat universe, assuming a cosmological constant with equation of state w = −1. Measurements of the present-day dark energy equation of state parameter, assuming standard general relativity (GR), are w = −1.020 ± 0.027 (Alam et al 2021) and w = −1.031 +0.030 −0.027 (Abbott et al 2022). Since the ΛCDM standard model of cosmology was established, the past 20 years have seen an explosive growth of cosmological observations that have continued to support the ΛCDM model with increasingly tight parameter constraints.…”

“…Since the ΛCDM standard model of cosmology was established, the past 20 years have seen an explosive growth of cosmological observations that have continued to support the ΛCDM model with increasingly tight parameter constraints. These recent measurement constraints on ΛCDM come from many types of observations, including the CMB (e.g., Hinshaw et al 2013;Planck Collaboration et al 2020a), Type Ia supernovae (SNe Ia; e.g., Scolnic et al 2018), baryon acoustic oscillations (BAO) in the galaxy distribution (e.g., Alam et al 2021;Eisenstein et al 2005), and weak gravitational lensing (Abbott et al 2022;Tröster et al 2021;Heymans et al 2021). Indeed, ΛCDM has survived so many observational tests that is difficult to believe that it can be very far off of reality.…”