DES: Recent Cosmology Results

DES: Recent Cosmology Results

DES Overview SE TRUTH == WF

EDI Initiatives
DES Papers
Milky Way Satellites and Dark Matter Physics
DES Cosmology Overview
Y3 Weak Lensing and Large-Scale Structure Results COADD TRUTH == 10x WF
Y6 Data for Cosmology, DR2
Updated Analysis Timeline

 Tom Diehl & Rich Kron @
 PAC June 10, 2021 DEEPEST > 100x WF

Dark Energy Survey Collaboration

Started in 2003, DES is an
International Collaboration
~700 people with diverse
scientific interests.

● DECam: The 570 Megapixel camera for the
 Blanco 4m telescope in Chile.
● Survey Observations 2013-2019 (Y3 2013-16).
● Wide field: 5000 sq. deg. in 5 bands. ~23
 magnitude.
● 27 sq. deg. 5-yr SNIa survey

Dark Energy Survey Collaboration

C.M. May 17-21, 2021 Focused on Y6 Plans (especially for Cosmology Key Projects) &
EDI/EPO. The Collaboration was enthusiastic and well-prepared, and looking forward to
meeting in-person (hopefully) next time.

Equity, Diversity, and Inclusion Initiatives

● Currently engaged with the NOVA Collective (HOME - The Nova Collective),
 ○ We recently completed a climate survey. We’ll get the results soon.
● Mentorship Program
 ○ Volunteer Mentors. 25 Mentor/Mentee pairs. A dedicated Mentorship Coordinator.

● Adjustments to DES Collaboration written policies so that engagement with
 underrepresented people in STEM is encouraged
● Focus at Collaboration Meeting
 ○ Plenary Speaker from outside DES
 ○ EDI Parallel Sessions: Connecting with minority-serving institutions, Focusing EPO efforts on
 inclusion, Giving Credit in DES
 ○ EDI One-slides at the beginning of every Plenary session

DES Publications Update
 91 DES PH.D’s
 (so far)

 https://dbweb8.fnal.gov:8443/DESPub/app/PB/pub/pbpublished

Through May 25, 2021, DES has 347 refereed science papers (not counting pre-data technical papers) with
14,700+ citations. Some of the recent papers (before May 25):
Instrumental: “A Machine Learning Approach to the Detection of Ghosting and Scattered Light Artifacts in Dark Energy Survey Images”, “Reducing
ground-based astrometric errors with Gaia and Gaussian processes” will both be useful to LSST
Solar System: “Testing the isotropy of the Dark Energy Survey's extreme trans-Neptunian objects”
SN1ae: “OzDES multifibre spectroscopy for the Dark Energy Survey: Results and implications for future surveys”, “The Effect of Environment on Type Ia
Supernovae in the Dark Energy Survey Three-Year Cosmological Sample”, “The Dark Energy Survey Supernova Program: Modelling selection efficiency
and observed core collapse supernova contamination”, “Rates and delay times of type Ia supernovae in the Dark Energy Survey”
Galaxy Clusters: “Is diffuse intracluster light a good tracer of the galaxy cluster matter distribution?”, “ * Masses: Weak Lensing Calibration of the Dark
Energy Survey Year 1 redMaPPer Clusters using Stellar Masses”, “The WaZP galaxy cluster sample of the Dark Energy Survey Year 1”
Weak Lensing: “Galaxy Clustering in Harmonic Space from the Dark Energy Survey Year 1 Data: Compatibility with Real Space Results”
Galaxy Clusters + WL: “Combination of cluster number counts and two-point correlations: Validation on Mock Dark Energy Survey”, “Dark Energy
Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations”
Galaxy Clusters + External Data: “Cosmological Constraints from DES Y1 Cluster Abundances and SPT Multi-wavelength data”, “Probing galaxy
evolution in massive clusters using ACT and DES: splashback as a cosmic clock”, “The Atacama Cosmology Telescope: A Catalog of > 4000 Sunyaev-
Zel'dovich Galaxy Clusters”
Modified Gravity: “Probing gravity with the DES-CMASS sample and BOSS spectroscopy”, “Galaxy-galaxy lensing with the DES-CMASS catalogue:
measurement and constraints on the galaxy-matter cross-correlation”
Optical + GW: “Constraints on the Physical Properties of S190814bv through Simulations based on DECam Follow-up Observations by DES”
Dark Matter: “Milky Way Satellite Census. III. Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies”, “Constraints on
Decaying Dark Matter with DES-Y1 and external data” .
Galaxy Evolution: “Galaxy Morphological Classification Catalogue of the Dark Energy Survey Year 3 data with Convolutional Neural Networks” 6

Current Standard Cosmological model: ΛCDM

Flat Universe with Dark
Energy in the form of a
cosmological constant Λ
+ Cold Dark Matter.

It assumes General
Relativity.

ΛCDM became the
standard model following
observations from Type
Ia Supernovae and the
Cosmic Microwave
Background.
 7

Missing Satellites Problem &
 Known MW satellites vs year

 Dark Matter Physics
 DECam

A long-time controversy: DM halo models Distribution of MW satellite masses
predict hundreds of captured “satellite” enables model-dependent constraints
galaxies for the Milky Way. DES data and on Dark Matter properties. i.e. DM must
selection function vs. magnitude (mass be massive.
proxy) shows that there are!

 Mass v. Mixing angle

 Absolute Magnitude
 Drlica-Wagner et al. ApJ 893, 1 (2020) Nadler et al. PRL 126, 091101 (2021)

Testing ΛCDM: Is the late time clustering compatible with the ΛCDM
 prediction assuming initial conditions from the CMB?

 Spheres
 with
 radius
 8 Mpc/h

As: Amplitude of primordial σ8: Amplitude of mass
scalar density fluctuations. fluctuations today, at 9
 distance 8 Mpc/h

DES: Cosmology Y1
 Y3 Spectr. SNIa + Y1
 3x2pt WL

 7 Ways
 DES, PRL 122, 171301 (2019)

Growth rate of structure and Expansion
History: Weak Gravitational Lensing, Galaxy
Clustering, & Galaxy Cluster Abundance
Expansion History: BAO (standard rulers), DES, PRD 102, 023509 (2020)
SNIa (standard candles), Gravitational Wave
Follow up (standard sirens), Strongly-Lensed Palmese et al. ApJL 900, L33 (2020) Time varying SL quasar
Transients. H0 = 74.2+2.7-3.0
 Standard km/s/Mpc
 Y1 Combo Sirens

 To et al. arxiv:20100.01138
 10
 Shahib et al., MNRAS 494, 6072 (2020)

New Results from DES: “Y3 3x2pt WL”
 Weak Gravitational Lensing: Sources and Lenses

Galaxies trace the Light from distant galaxies
underlying dark matter passes the foreground
structure : they are structures and acquires
observed to be spatially coherent distortions : they
clustered. We construct a are observe to be lensed.
power spectrum, or real- We correlate the lensing
space correlation function of sources by the
of the positions of foreground objects in
(foreground) lens galaxies redshift / redshift bins (position-
in redshift bins (position- distance shear).
position). Image plane
 We also measure the
 correlation of the shapes
 Cosmic Shear : shape-shape (shear-shear) of source galaxy pairs as a
 Galaxy Clustering : position-position 3x2pt function of angular radius
 2x2pt
 Galaxy-Galaxy Lensing : position-shear and redshift (shear-shear). 11

Y3 “3x2pt” Methodology: Pixels to Cosmology
 Webinar from May 27, 2021 https://www.youtube.com/watch?v=8aHbLMUOwLc

 12
LCDM —— WL+LSS —— Redshifts —— Shapes —— Clustering — Simulations —— Theory —— Results

Y3 WL 3x2-pt “29” Papers
 in https://www.darkenergysurvey.org/des-year-3-cosmology-results-papers/

1. “Blinding Multi-probe Cosmological Experiments” J. Muir, G. M. Bernstein, D. Huterer et al., arXiv: 1911.05929, MNRAS 494 (2020) 4454
2. “Photometric Data Set for Cosmology”, I. Sevilla-Noarbe, K. Bechtol, M. Carrasco Kind et al., arXiv:2011.03407, ApJS 254 (2021) 24
3. “Weak Lensing Shape Catalogue”, M. Gatti, E. Sheldon, A. Amon et al., arXiv:2011.03408, MNRAS 504 (2021) 4312
4. “Point Spread Function Modelling”, M. Jarvis, G. M. Bernstein, A. Amon et al., arXiv:2011.03409, MNRAS 501 (2021) 1282
5. “Measuring the Survey Transfer Function with Balrog”, S. Everett, B. Yanny, N. Kuropatkin et al., arXiv:2012.12825
6. “Deep Field Optical + Near-Infrared Images and Catalogue”, W. Hartley, A. Choi, A. Amon et al., arXiv:2012.12824
7. “Blending Shear and Redshift Biases in Image Simulations”, N. MacCrann, M. R. Becker, J. McCullough et al., arXiv:2012.08567
8. “Redshift Calibration of the Weak Lensing Source Galaxies”, J. Myles, A. Alarcon, A. Amon et al., arXiv:2012.08566
9. “Redshift Calibration of the MagLim Lens Sample using Self-Organizing Maps and Clustering Redshifts”, G. Giannini et al., in prep.
10. “Clustering Redshifts – Calibration of the Weak Lensing Source Redshift Distributions with redMaGiC and BOSS/eBOSS”, M. Gatti, G. Giannini, et al., arXiv:2012.08569
11. “Calibration of Lens Sample Redshift Distributions using Clustering Redshifts with BOSS/eBOSS”, R. Cawthon et al. arXiv:2012.12826
12. “Phenotypic Redshifts with SOMs: a Novel Method to Characterize Redshift Distributions of Source Galaxies for Weak Lensing Analysis” R. Buchs, C.Davis, D. Gruen et al. MNRAS 489 (2019) 820
13. “Marginalising over Redshift Distribution Uncertainty in Weak Lensing Experiments”, J. Cordero, I. Harrison et al., in prep.
14. “Exploiting Small-Scale Information using Lensing Ratios”, C. Sánchez, J. Prat et al., in prep.
15. “Cosmology from Combined Galaxy Clustering and Lensing - Validation on Cosmological Simulations”, J. de Rose et al., in prep.
16. “Unbiased fast sampling of cosmological posterior distributions”, P. Lemos, R. Rollins, N. Weaverdyck, A. Ferte, A. Liddle et al., in prep.
17. “Assessing Tension Metrics with DES and Planck Data”, P. Lemos, M. Raveri, A. Campos et al., arXiv:2012.09554
18. “Dark Energy Survey Internal Consistency Tests of the Joint Cosmological Probe Analysis with Posterior Predictive Distributions”, C. Doux, E. Baxter, P. Lemos et al. MNRAS 503 (2021) 2688
19. “Covariance Modelling and its Impact on Parameter Estimation and Quality of Fit”, O. Friedrich, F. Andrade-Oliveira, H. Camacho et al., arXiv:2012.08568
20. “Multi-Probe Modeling Strategy and Validation”, E. Krause et al., in prep.
21. “Curved-Sky Weak Lensing Map Reconstruction”, N. Jeffrey, M. Gatti, C. Chang et al., in prep.
22. “Galaxy Clustering and Systematics Treatment for Lens Galaxy Samples”, M.Rodríguez-Monroy, N. Weaverdyck, J. Elvin-Poole, M. Crocce et al., in prep.
23. “Optimizing the Lens Sample in Combined Galaxy Clustering and Galaxy-Galaxy Lensing Analysis”, A. Porredon, M. Crocce et al., arXiv:2011.03411 PhRvD 103 (2021) 043503
24. “High-Precision Measurement and Modeling of Galaxy-Galaxy Lensing”, J. Prat, J. Blazek, C. Sánchez et al., in prep.
25. “Constraints on Cosmological Parameters and Galaxy Bias Models from Galaxy Clustering and Galaxy-Galaxy Lensing using the redMaGiC Sample”, S. Pandey et al., in prep.
26. “Cosmological Constraints from Galaxy Clustering and Galaxy-Galaxy Lensing using the Maglim Lens Sample” A. Porredon, M. Crocce et al., in prep.
27. “Cosmology from Cosmic Shear and Robustness to Data Calibration”, A. Amon, D. Gruen, M. A. Troxel et al., in prep.
28. “Cosmology from Cosmic Shear and Robustness to Modeling Assumptions”, L. Secco, S. Samuroff et al., in prep.
29. “Magnification modeling and impact on cosmological constraints from galaxy clustering and galaxy-galaxy lensing”, J. Elvin-Poole, N. MacCrann et al., in prep.
30. “Cosmological Constraints from Galaxy Clustering and Weak Lensing” The DES Collaboration in prep.
 13
 So many papers because there is innovation in every analysis step

Two Lens Samples N(z)

● redMagic: LRG selection 2.9M galaxies in 5
 redshift bins
● MagLim: Brightness selection 10.1M in 6
 redshift bins
● Below: galaxy clustering (position-position)
 Weights correct for effects of
 airmass, seeing, exposure time, depth,
 stellar density, dust, sky brightness,
 calibration residuals
 Myles, Alarcon et al. (2021),
 Porredon et al. (2021),
 Gatti, Giannini et al. (2021),
 Sanchez, Prat et al. (2021),
 Cordero, Harrision et al. (2021),
 Cawthon et al. (2021),
 de Vicente et al (2015)
 Rodriguez-Monroy et al. (2021) 14
 Everett et al. (2020), ++

100.2 M source galaxy shapes for DES Y3
 DES Science Verification: 2-3 million shapes, DES Y1: 34.8 million

 Stars

 Many more source galaxy shapes than
 any previous analysis
 Galaxies
 Key improvements over DES Y1:
 ● More sky
 ● More accurate PSF models (Piff,
 Jarvis+2020) => better shear
 measurements
 ● Improved astrometry
 ● Expanded suite of null tests (Gatti,
 Sheldon+2021)
PDF

 ● Effects of deblending systematic
 (MacCrann+ 2021)
 15

Position-Shear Measurements
 Galaxy-Galaxy lensing around foreground galaxies

The two-point function between lens galaxy positions and source galaxy tangential shear.

 Shown for MagLim
 Prat et al. (2021)

The Correlation of Pairs of Galaxy Shapes

 Amon et al. 2021

 ξ− estimator of cosmic shear
 Secco, Samuroff et al. 2021
 ξ+ estimator of cosmic shear

 Final results from a Blinded Fit:
 Cosmology (7 params)
 Astrophysical Model (9 params)
 Calibration (16 params)
ξ±: ΕΕ ± ΒΒ Detection significance ~27 (Y1) → 40 (Y3)
 17

MagLim
 Y3 Weak Lensing
 Cosmology Results

 S8 == σ8 (Ωm/0.3)0.5
 ΛCDM

 wCDM

• MagLim and redMaGiC 3x2 in perfect agreement
• Evidence for potential systematics in the
 redMaGiC clustering data vector at all redshifts
 and above the fiducial lens redshift range for
 MagLim. Press Release: https://news.fnal.gov/2021/05/dark-energy-
 survey-releases-most-precise-look-at-the-universes-evolution/
 arXiv:2105.13549 DES Collaboration (2021)

Combinations
 We find no significant evidence for inconsistency in Λ CDM between DES 3x2pt and Planck, and
 good agreement between DES + other complementary low-redshift probes and Planck.

arXiv:2105.13549 DES Collaboration (2021)
 “Low-redshift non-
 lensing data” is
 SNe Ia (but not DES),
 BAO, RSD

 ΛCDM

 + DES

 wCDM

DES Y6 Data is Amazing!
 https://des.ncsa.illinois.edu/releases/dr2
 Exposures/Unit
 Area
 Y6 more homogenous than Y3 (typically 8 vs. 4)
 Y3 -> Y6 depth increase by completeness ~ 0.7 mag
 (partly attributed to detection threshold adjustments)
 400M objects -> 700M objects

 Uniform
 coverage

 Deeper

 20

https://arxiv.org/abs/2101.05765

 Y6 Data Release 2 Quality Highlights
 DR2 made public in January 2021 (as scheduled 3 years prior).

Sufficient astrometric precision to see signature of
 Relative photometric uniformity to ~2 mmag evaluated with respect to Gaia
stellar proper motions in DES internal astrometry.
 Presented two absolute photometric calibration methods based on
With full astrometric solutions (not released in DR2),
 CALSPEC standard and sample of 150 DA white dwarfs. DES photometry
precision limited by atmosphere, typically ~10 milli-
 tied to AB magnitude system with ~10 mmag accuracy.
arcsec RMS in a single exposure 21

Analysis Timeline Goals

● Winter 2020: Y1 Galaxy Cluster Cosmology Submitted February 20, 2020. Done.
● Fall 2020: Y3 3x2pt early papers on Infrastructure/Methods. Done.
● January 2021: Data Release 2 → Based on Y6A2 Done
● Winter 2021: Y3 3x2pt Cosmology. Done.
● Spring 2021: Y6A2 Gold data product available to DES. Done.
● Summer 2021: Joint constraints from Y3 3x2pt+BAO+Y3 SNe probes.
● Summer 2021: Y3 Combined Probes (with data samples external to DES such as South Pole Telescope, among others).
● Fall 2021: Y3 Galaxy Cluster Cosmology.
● Fall 2021: Y3A2 Gold Public Release
● Winter 2021-2022: Y5 SN Cosmology and combinations with Y3 DES analyses.
● Spring 2022: Y6 WL Shear Catalogs from data available.
● Summer 2022: Y6 Cosmology Forecasts - estimates of the ultimate size of uncertainties on cosmological parameters
 for Snowmass.
● January 2023: Y6 3x2pt Infrastructure/Methods early papers submissions begin.
● Summer 2023: Y6 3x2-pt Cosmology. A goal of 2+ years, noting that both Y1 and Y3 3x2-pt WL analyses took 3+
 years, is speculative.
● Summer 2024: Y6 Cosmology Analyses Complete.
 22

Summary

● DES has a diverse scientific program including Solar System, Milky Way, Extra-galactic, and
 cosmological science.
We study cosmology “7 ways”. That some are sensitive to growth rate of structure and the expansion
history, and others just to the expansion history is a strength.
● We summarized the technique and cosmological results of the Y3 “Weak Lensing and Large- Scale
 Structure “3x2pt” analysis.
 ○ The Unprecedented Y3 data sample required the development of novel methods at every stage
 ○ We find no significant evidence for inconsistency in ΛCDM between DES 3x2pt and Planck, and good
 agreement between DES + other complementary low-redshift probes and Planck.
● DES Y6 data is fantastic, and we are initiating the Y6 cosmology analyses
 ○ There is a significant work ahead to understand the puzzling apparent decorrelation between the
 clustering and lensing amplitudes, which signal potential photometric systematics, but do not currently
 significantly impact ΛCDM cosmology.

Incomplete Credits