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DES
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The Dark Energy Survey (DES) is a large-scale imaging survey designed to probe cosmological structure through multiple two-point correlation functions. present…
The Dark Energy Survey (DES) is a large-scale imaging survey designed to probe cosmological structure through multiple two-point correlation functions.1Abbott et al. (2022)1present cosmology results from 5000 deg² of imaging data, combining cosmic shear, galaxy clustering, and galaxy-galaxy lensing to constrain cosmological parameters within flat ΛCDM and wCDM models.2
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Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensingT. M. C. Abbott, M. Aguena et al.2022Physical review. D/Physical review. D.
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KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensingH. Hildebrandt, Massimo Viola et al.2016Monthly Notices of the Royal Astronomical Society
View - Cosmic Shear — A weak gravitational lensing technique using correlations in galaxy ellipticities to probe the large-scale matter distribution; DES Year 3 used 100 million source galaxies for this measurement.
- Galaxy Clustering — The spatial distribution of lens galaxies used as a tracer of the underlying dark matter field, combined with shear in the DES 3×2pt analysis.
- S₈ Parameter — A derived cosmological parameter S₈ ≡ σ₈√(Ωm/0.3) used to quantify the amplitude of matter fluctuations; KiDS-450 found S₈ = 0.745 ± 0.039, in 2.3-σ tension with Planck 2015.
- 3×2pt Analysis — A joint analysis of three two-point statistics (cosmic shear, galaxy clustering, galaxy-galaxy lensing) that maximises cosmological information from imaging surveys.
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Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensingT. M. C. Abbott, M. Aguena et al.2022Physical review. D/Physical review. D.
View 2
KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensingH. Hildebrandt, Massimo Viola et al.2016Monthly Notices of the Royal Astronomical Society
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Detection of large-scale intrinsic ellipticity--density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveysR. Mandelbaum, C. M. Hirata et al.2006Monthly Notices of the Royal Astronomical Society
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Evolution of the dark matter distribution with three-dimensional weak lensingD. Bacon, A. Taylor et al.2004Monthly Notices of the Royal Astronomical Society
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Diagram
DES Imaging Data (5000 deg²) | ┌──────┴──────────────────┐ | | Source Galaxies Lens Galaxies (~100 million) (two independent samples) | | Shear Measurement Galaxy Clustering | | └──────┬──────────────────┘ | Galaxy-Galaxy Lensing (cross-correlation) | ┌──────┴──────────────────┐ | 3×2pt Joint Analysis | └──────┬──────────────────┘ | Cosmological Parameter Inference (flat ΛCDM / wCDM, 25 nuisance parameters)
Table
| Feature | DES Year 3 | KiDS-450 |
|---|---|---|
| Survey Area | ~5000 deg² | ~450 deg² |
| Source Galaxies | ~100 million | ~15 million |
| Analysis Type | 3×2pt (shear + clustering + GGL) | Tomographic cosmic shear |
| Cosmological Models | flat ΛCDM, wCDM | flat ΛCDM |
| Nuisance Parameters | 25 | Not specified |
| Key Tension | Reported vs. Planck | 2.3-σ in S₈ vs. Planck 2015 |
DES Year 3 required updates to nearly every part of the analysis pipeline from Year 1, including modeling advances and novel improvements in shear calibration and photometric redshift inference.1KiDS-450 used a self-calibrating version of lensfit validated with image simulations, with redshift calibration confirmed via angular cross-correlations.2
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Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensingT. M. C. Abbott, M. Aguena et al.2022Physical review. D/Physical review. D.
View 2
KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensingH. Hildebrandt, Massimo Viola et al.2016Monthly Notices of the Royal Astronomical Society
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- The DES analysis required marginalisation over 25 nuisance parameters, reflecting significant systematic uncertainties in shear calibration and photometric redshift inference.
- Intrinsic alignments of galaxy ellipticities — both the II (intrinsic-intrinsic) and GI (gravitational shear-intrinsic ellipticity) correlations — represent a potential source of systematic error in weak lensing surveys such as DES.
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Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensingT. M. C. Abbott, M. Aguena et al.2022Physical review. D/Physical review. D.
View 2
Detection of large-scale intrinsic ellipticity--density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveysR. Mandelbaum, C. M. Hirata et al.2006Monthly Notices of the Royal Astronomical Society
View - DES Year 3 is the first cosmology result from large-scale structure using the full 5000 deg² DES Data Release 1 footprint.
- The 3×2pt methodology jointly analyses cosmic shear, galaxy clustering, and galaxy-galaxy lensing for tighter cosmological constraints.
- KiDS-450 found a 2.3-σ tension in S₈ with Planck 2015, a discordance also relevant to interpreting DES results.
- Intrinsic alignment systematics must be carefully modelled in any weak lensing cosmology analysis.
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Dark Energy Survey Year 3 results: Cosmological constraints from galaxy clustering and weak lensingT. M. C. Abbott, M. Aguena et al.2022Physical review. D/Physical review. D.
View 2
Optimal Factorization of Cosmological Large-Scale Structure Observables.Bakx Thomas, Chisari Nora Elisa et al.2025Physical review letters
View 3
KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensingH. Hildebrandt, Massimo Viola et al.2016Monthly Notices of the Royal Astronomical Society
View 4
Detection of large-scale intrinsic ellipticity--density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveysR. Mandelbaum, C. M. Hirata et al.2006Monthly Notices of the Royal Astronomical Society
View Want to research your own topic? Try it free →
- "DES Year 3 S8 tension with Planck CMB constraints"
- "Photometric redshift calibration methods for weak lensing surveys"
- "Intrinsic alignment modelling in Stage IV dark energy surveys"
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