Dark Energy Survey

Dark Energy Survey
Felipe Menanteau and the Dark Energy Survey Collaboration · CC BY-SA 4.0 · source
Name	Dark Energy Survey
Caption	The Dark Energy Camera mounted on the Victor M. Blanco 4-meter Telescope
Established	2008
Location	Cerro Tololo Inter-American Observatory, Chile
Wavelength	Optical
Instrument	Dark Energy Camera
Telescope	Victor M. Blanco 4-meter Telescope
Participants	Fermilab, Lawrence Berkeley National Laboratory, University of Chicago, University of Cambridge, Harvard University

Dark Energy Survey The Dark Energy Survey was a multinational astronomical project designed to map hundreds of millions of galaxies, detect thousands of supernovae, and probe cosmic structure to constrain the nature of dark energy, dark matter, and cosmological parameters. The project used the Dark Energy Camera on the Victor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, and involved institutions including Fermilab, Lawrence Berkeley National Laboratory, University of Chicago, University of Cambridge, and Harvard University. Observations between 2013 and 2019 generated large imaging datasets that supported analyses linked to the Lambda-CDM model, cosmic microwave background, and large-scale structure surveys like the Sloan Digital Sky Survey and Euclid (spacecraft) planning.

Overview

The project was commissioned by a consortium including Fermilab, National Science Foundation, Department of Energy (United States), University of Michigan, and international partners such as ETH Zurich, University of Edinburgh, Australian National University, and University of São Paulo. Its primary instrument, the Dark Energy Camera, was developed with contributions from DOE's Office of Science, Baylor University, University of Illinois Urbana-Champaign, University of Pennsylvania, and University of Arizona. Survey strategy emphasized wide-field optical imaging across five filters to complement efforts by space missions like Planck (spacecraft), Hubble Space Telescope, and ground-based projects such as the Subaru Telescope and Very Large Telescope.

Scientific Goals and Objectives

DES aimed to measure cosmic acceleration and constrain the equation of state of dark energy through four primary probes: galaxy cluster counts, weak gravitational lensing, baryon acoustic oscillations, and type Ia supernovae. The collaboration sought to test models including the Lambda-CDM model, alternatives like quintessence, and modifications exemplified by f(R) gravity and Brans–Dicke theory. Cross-correlation studies interfaced DES results with datasets from WMAP, Planck (spacecraft), Atacama Cosmology Telescope, South Pole Telescope, and spectroscopic surveys such as Baryon Oscillation Spectroscopic Survey and Dark Energy Spectroscopic Instrument planning.

Instrumentation and Observations

Central hardware included the Dark Energy Camera, a 570-megapixel wide-field imager built with CCDs from Lawrence Berkeley National Laboratory and optics supplied by NOAO. The camera was installed on the Victor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory, operated by the National Optical Astronomy Observatory and later NOIRLab. Observing campaigns covered ~5000 square degrees using five photometric bands (g,r,i,z,Y) coordinated with calibration programs referencing photometric standards from Pan-STARRS, Gaia (spacecraft), and SDSS. Nightly operations interfaced with scheduling systems developed with teams at Fermilab, SLAC National Accelerator Laboratory, and University of Pennsylvania.

Data Processing and Analysis

Data pipelines were implemented using frameworks from Fermilab and Lawrence Berkeley National Laboratory and relied on software libraries and platforms such as AstroPy, HEALPix, SExtractor, PSFEx, and the Science Data Management (DESDM) system. Image reduction, astrometric calibration, photometric calibration, artifact rejection, and coaddition used processing centers at NCSA, NCSA (Beckman Institute), Fermilab, and partner university clusters. Catalog products were cross-matched with external resources like Two Micron All Sky Survey, WISE, GALEX, and spectroscopic training sets from Sloan Digital Sky Survey and VIPERS for photometric redshift estimation using machine learning teams at University of Chicago and University College London.

Key Results and Discoveries

DES produced influential measurements: weak lensing shear catalogs that constrained matter density and clustering amplitude relative to Planck (spacecraft) CMB results; detection and mass characterization of galaxy clusters using optical richness consistent with results from XMM-Newton and Chandra X-ray Observatory; discovery of numerous Type Ia supernova light curves improving distance ladders alongside Supernova Legacy Survey data; and identification of dwarf satellite candidates around the Milky Way complementing findings from Dark Energy Camera Legacy Survey and Gaia (spacecraft). The survey produced catalogs used in cross-correlation with Fermi Gamma-ray Space Telescope for dark matter annihilation limits and informed forecasts for Euclid (spacecraft), Nancy Grace Roman Space Telescope, and Vera C. Rubin Observatory surveys.

Collaboration and Organization

The collaboration encompassed universities and laboratories including Fermilab, Lawrence Berkeley National Laboratory, Kavli Institute for Cosmological Physics, University of Cambridge, Harvard University, MIT, Stanford University, University of Chicago, University of Edinburgh, University of Pennsylvania, University of Michigan, University of Washington, University of Arizona, University of Toronto, Carnegie Mellon University, University of British Columbia, University of Sao Paulo, ANU, ETH Zurich, Max Planck Society, and many others. Governance featured an executive board, science committees for weak lensing, clusters, supernovae, and large-scale structure, and working groups coordinating with funding agencies such as the National Science Foundation and DOE. Education and public outreach activities collaborated with institutions including Smithsonian Astrophysical Observatory and Space Telescope Science Institute.

Legacy and Impact on Cosmology

DES legacy includes publicly released image and catalog archives that serve as benchmarks for methods in weak lensing, photometric redshifts, and survey calibration used by successors like the Vera C. Rubin Observatory Legacy Survey of Space and Time and missions like Euclid (spacecraft) and Nancy Grace Roman Space Telescope. Its techniques influenced instrument development at NOIRLab and survey coordination models for multinational consortia including LSST Corporation and International Astronomical Union working groups. The survey's datasets underpinned hundreds of peer-reviewed publications shaping contemporary debate on tensions between low-redshift probes and Planck (spacecraft) CMB cosmology, informing theoretical work in Lambda-CDM model extensions and tests of General relativity on cosmological scales.

Category:Observational cosmology