Dark Energy Survey Year 6 Results: Photometric Data Set for Cosmology

TL;DR

The paper presents the Dark Energy Survey Year 6 photometric data set, which offers a large, well-calibrated, and high-quality galaxy catalog optimized for cosmological research, with improved measurements and classifications.

Contribution

It introduces the Y6 Gold data set with enhanced calibration, object classification, and redshift estimation, building upon DES DR2 for cosmology analyses.

Findings

Nearly 5000 deg² of imaging data included

Galaxy and star samples with high classification accuracy

Improved photometric redshift and shape measurements

Abstract

We describe the photometric data set assembled from the full six years of observations by the Dark Energy Survey (DES) in support of static-sky cosmology analyses. DES Y6 Gold is a curated data set derived from DES Data Release 2 (DR2) that incorporates improved measurement, photometric calibration, object classification and value added information. Y6 Gold comprises nearly $5000~{\rm deg}^2$ of $grizY$ imaging in the south Galactic cap and includes 669 million objects with a depth of $i_{AB} \sim 23.4$ mag at S/N $\sim 10$ for extended objects and a top-of-the-atmosphere photometric uniformity $< 2~{\rm mmag}$. Y6 Gold augments DES DR2 with simultaneous fits to multi-epoch photometry for more robust galaxy shapes, colors, and photometric redshift estimates. Y6 Gold features improved morphological star-galaxy classification with efficiency $98.6\%$ and contamination $0.8\%$ for galaxies with $17.5 < i_{AB} < 22.5$. Additionally, it includes per-object quality information, and accompanying maps of the footprint coverage, masked regions, imaging depth, survey conditions, and astrophysical foregrounds that are used for cosmology analyses. After quality selections, benchmark samples contain 448 million galaxies and 120 million stars. This paper will be complemented by online data access and documentation.