Dark Energy Survey Year 3 results: Cosmology from cosmic shear and robustness to modeling uncertainty

Abstract

This work and its companion paper, Amon et al. [Phys. Rev. D 105, 023514 (2022)], present cosmic shear measurements and cosmological constraints from over 100 million source galaxies in the Dark Energy Survey (DES) Year 3 data. We constrain the lensing amplitude parameter S 8 ≡ σ 8 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Ω m =0.3 p at the 3% level in ΛCDM: S 8 ¼ 0.759 þ0.025 −0.023 (68% CL). Our constraint is at the 2% level when using angular scale cuts that are optimized for the ΛCDM analysis: S 8 ¼ 0.772 þ0.018 −0.017 (68% CL). With cosmic shear alone, we †

Dark Energy Survey Year 3 results: Cosmology from cosmic shear and robustness to data calibration

“…This work presents the cosmological constraints from cosmic-shear measurements with the DES wide-field survey, using data taken during its first three years of observations, and presents its robustness to data calibration. A companion paper to this work, Secco, Samuroff et al [98], demonstrates the robustness of these cosmic-shear cosmological constraints to modeling choices, in particular, to intrinsic alignments, baryonic effects, higher-order lensing effects and neutrinos. Cosmic shear is analyzed using a common framework with those from galaxy-galaxy lensing (Prat et al [99]) and galaxy clustering (Rodríguez-Monroy et al [100]), combined as 2 × 2pt in Porredon et al [101], Pandey et al [102], and Elvin-Poole, MacCrann et al [103] in a joint DES Y3 3 × 2pt analysis presented in DES Collaboration [104].…”

“…After eliminating the small scales, in order to mitigate model uncertainties in the cosmology analysis, as motivated in Sec. VII C [98,111], the measurement is found to have an S=N ¼ 27. Using the ΛCDM-Optimized scale selection, described in Sec.…”

“…Systematic errors in the model are demonstrated to be subdominant to the precision of the data, in order to derive unbiased cosmological parameters [111], as validated specifically for cosmic shear in Ref. [98]. Cosmological, astrophysical, and systematic parameters are constrained for the ΛCDM model.…”

Intrinsic alignments of the extended radio continuum emission of galaxies in the EAGLE simulations

“…Further moti v ation for modelling intrinsic alignment arises from its putative sensitivity to a diverse range of physical influences, such as the growth of angular momentum during galaxy formation (Lee & Pen 2000 ), primordial gra vitational wa ves ( As the depth and fidelity of observations impro v es, commensurate impro v ements in the ability of weak lensing surv e ys to constrain cosmological parameters are increasingly limited by an incomplete understanding of the effect of baryons on the matter power spectrum and the intrinsic alignment of galaxies. Amon et al ( 2022 ) argue that such uncertainties cost the Dark Energy Surv e y Year 3 (DES Y3; Secco et al 2022 ) cosmic shear measurements approximately two-thirds of their constraining power. Intrinsic alignments have been estimated primarily using the analytic linear alignment model (Catelan, Kamionkowski & Blandford 2001 ;Hirata & Seljak 2004 ), with the ansatz that the projected shapes of galaxies are linearly correlated with the projected tidal field.…”

“…Contemporary weak lensing experiments are dominated by optical/near-IR surv e ys, since to date only these have delivered imaging with the necessary source density required to extract a robust shear measurement. Successive data releases from the Kilo-Degree Surv e y (KiDS) hav e pro vided galaxy counts of ∼10 arcmin −2 o v er 450 and 1350 de g 2 , respectiv ely, (Hildebrandt et al 2017 ;He ymans et al 2021 ), while the DES Y3 data set contains galaxy sources at 5.59 arcmin −2 o v er 4143 de g 2 (Secco et al 2022 ). In principle, ho we ver, shear measurements can also be made using the extended radio continuum emission of the interstellar medium.…”