KiDS+VIKING-450 and DES-Y1 combined: Mitigating baryon feedback uncertainty with COSEBIs

We present cosmological constraints from a joint cosmic shear analysis of the Kilo-Degree Survey (KV450) and the Dark Energy Survey (DES-Y1), which were conducted using Complete Orthogonal Sets of E/B-Integrals (COSEBIs). With COSEBIs, we isolated any B-modes that have a non-cosmic shear origin and demonstrate the robustness of our cosmological E-mode analysis as no significant B-modes were detected. We highlight how COSEBIs are fairly insensitive to the amplitude of the non-linear matter power spectrum at high k-scales, mitigating the uncertain impact of baryon feedback in our analysis. COSEBIs, therefore, allowed us to utilise additional small-scale information, improving the DES-Y1 joint constraints on S8 = σ8(Ωm/0.3)0.5 and Ωm by 20%. By adopting a flat ΛCDM model we find S8 = 0.755−0.021+0.019, which is in 3.2σ tension with the Planck Legacy analysis of the cosmic microwave background.

Download Full-text

KiDS+VIKING-450 and DES-Y1 combined: Cosmology with cosmic shear

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936154 ◽

2020 ◽

Vol 638 ◽

pp. L1 ◽

Cited By ~ 13

Author(s):

S. Joudaki ◽

H. Hildebrandt ◽

D. Traykova ◽

N. E. Chisari ◽

C. Heymans ◽

...

Keyword(s):

Dark Energy ◽

Cosmic Microwave Background ◽

Gravitational Lensing ◽

Error Model ◽

Calibration Error ◽

Microwave Background ◽

Weak Gravitational Lensing ◽

Dark Energy Survey ◽

Cosmic Shear ◽

Energy Survey

We present a combined tomographic weak gravitational lensing analysis of the Kilo Degree Survey (KV450) and the Dark Energy Survey (DES-Y1). We homogenize the analysis of these two public cosmic shear datasets by adopting consistent priors and modeling of nonlinear scales, and determine new redshift distributions for DES-Y1 based on deep public spectroscopic surveys. Adopting these revised redshifts results in a 0.8σ reduction in the DES-inferred value for S8, which decreases to a 0.5σ reduction when including a systematic redshift calibration error model from mock DES data based on the MICE2 simulation. The combined KV450+DES-Y1 constraint on S8 = 0.762−0.024+0.025 is in tension with the Planck 2018 constraint from the cosmic microwave background at the level of 2.5σ. This result highlights the importance of developing methods to provide accurate redshift calibration for current and future weak-lensing surveys.

Download Full-text

Dark Energy Survey Year 1 results: Cosmological constraints from cosmic shear

Physical Review D ◽

10.1103/physrevd.98.043528 ◽

2018 ◽

Vol 98 (4) ◽

Cited By ~ 186

Author(s):

M. A. Troxel ◽

N. MacCrann ◽

J. Zuntz ◽

T. F. Eifler ◽

E. Krause ◽

...

Keyword(s):

Dark Energy ◽

Cosmological Constraints ◽

Dark Energy Survey ◽

Cosmic Shear ◽

Energy Survey

Download Full-text

x -cut Cosmic shear: Optimally removing sensitivity to baryonic and nonlinear physics with an application to the Dark Energy Survey year 1 shear data

Physical Review D ◽

10.1103/physrevd.103.043531 ◽

2021 ◽

Vol 103 (4) ◽

Author(s):

Peter L. Taylor ◽

Francis Bernardeau ◽

Eric Huff

Keyword(s):

Dark Energy ◽

Dark Energy Survey ◽

Cosmic Shear ◽

Energy Survey

Download Full-text

Dark energy survey internal consistency tests of the joint cosmological probes analysis with posterior predictive distributions

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab526 ◽

2021 ◽

Vol 503 (2) ◽

pp. 2688-2705

Author(s):

C Doux ◽

E Baxter ◽

P Lemos ◽

C Chang ◽

A Alarcon ◽

...

Keyword(s):

Dark Energy ◽

Internal Consistency ◽

Goodness Of Fit ◽

Small Scale ◽

P Value ◽

Posterior Predictive Distribution ◽

Data Set ◽

Dark Energy Survey ◽

Data Vector ◽

Energy Survey

ABSTRACT Beyond ΛCDM, physics or systematic errors may cause subsets of a cosmological data set to appear inconsistent when analysed assuming ΛCDM. We present an application of internal consistency tests to measurements from the Dark Energy Survey Year 1 (DES Y1) joint probes analysis. Our analysis relies on computing the posterior predictive distribution (PPD) for these data under the assumption of ΛCDM. We find that the DES Y1 data have an acceptable goodness of fit to ΛCDM, with a probability of finding a worse fit by random chance of p = 0.046. Using numerical PPD tests, supplemented by graphical checks, we show that most of the data vector appears completely consistent with expectations, although we observe a small tension between large- and small-scale measurements. A small part (roughly 1.5 per cent) of the data vector shows an unusually large departure from expectations; excluding this part of the data has negligible impact on cosmological constraints, but does significantly improve the p-value to 0.10. The methodology developed here will be applied to test the consistency of DES Year 3 joint probes data sets.

Download Full-text