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

Abstract

This work, together with its companion paper, Secco, Samuroff et al. [Phys. Rev. D 105, 023515 (2022)], present the Dark Energy Survey Year 3 cosmic-shear measurements and cosmological constraints based on an analysis of over 100 million source galaxies. With the data spanning 4143 deg 2 on the sky, divided into four redshift bins, we produce a measurement with a signal-to-noise of 40. We conduct a blind analysis in the context of the Lambda-Cold Dark Matter (ΛCDM) model and find a 3% constraint of the clustering amplitude, S 8 ≡ σ 8 ðΩ m =0.3Þ 0.5 ¼ 0.759 þ0.025 −0.023 . A ΛCDM-Optimized analysis, which safely includes smaller scale information, yields a 2% precision measurement of S 8 ¼ 0.772 þ0.018 −0.017 that is consistent with the fiducial case. The two low-redshift measurements are statistically consistent with the Planck Cosmic Microwave Background result, however, both recovered S 8 values are lower than the highredshift prediction by 2.3σ and 2.1σ (p-values of 0.02 and 0.05), respectively. The measurements are shown to be internally consistent across redshift bins, angular scales and correlation functions. The analysis is demonstrated to be robust to calibration systematics, with the S 8 posterior consistent when varying the choice of redshift calibration sample, the modeling of redshift uncertainty and methodology. Similarly, we find that the corrections included to account for the blending of galaxies shifts our best-fit S 8 by 0.5σ without incurring a substantial increase in uncertainty. We examine the limiting factors for the precision of the cosmological constraints and find observational systematics to be subdominant to the modeling of astrophysics. Specifically, we identify the uncertainties in modeling baryonic effects and intrinsic alignments as the limiting systematics.

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

“…Likewise, errors in the estimation of galaxy redshift distributions nðzÞ can subtly alter the interpretation of the lensing measurement, both in terms of cosmology and of IAs. Amon et al [72] demonstrate that these measurement systematic errors are well controlled in the Y3 cosmic shear analysis. We note that the main cosmological constraints presented in both papers are identical.…”

“…The cosmic shear analysis presented in this paper, and in Amon et al [72], is part of a series of Year 3 cosmological results from large-scale structure produced by the Dark Energy Survey Collaboration. This work relies on many companion papers that validate the data, catalogs and theoretical methods; those papers, as well as this one, feed into the main "3 × 2pt" constraints, which combine cosmic shear with galaxy-galaxy lensing and galaxy clustering in ΛCDM and wCDM [73], as well as extended cosmological parameter spaces [74].…”

“…Our companion paper [72] presents a detailed investigation of observational errors that can similarly bias cosmological inference. Undiagnosed biases in the shear measurement process, for example, can lead one to incorrectly infer the lensing amplitude.…”

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.…”

The halo model with beyond-linear halo bias: unbiasing cosmological constraints from galaxy-galaxy lensing and clustering

“…One finding is that galaxy-galaxy lensing measurements are significantly lower than their prediction given a best-fitting halo model to galaxy clustering data (Leauthaud et al 2017;Lange et al 2019;Wibking et al 2020;Lange et al 2021). As this comparison typically assumes the Planck Collaboration et al (2020) best-fit cosmology, this may be another sign that the amount of late-time clustering predicted by the CMB does not match the amount of clustering from late-time observations (Heymans et al, 2013;Hildebrandt et al 2017;Hikage et al, 2019;Asgari et al 2021;Amon et al 2022; Secco, Samuroff ★ E-mail: mahony@astro.rub.de Krolewski et al 2021;White et al 2021;Chen et al 2021;Amon, Robertson et al prep). It may also, however, reflect missing ingredients in the standard galaxy-halo model (Leauthaud et al 2017;Lange et al 2019;Yuan et al 2020;Amon, Robertson et al prep).…”