Everett, S;
Yanny, B;
Kuropatkin, N;
Huff, EM;
Zhang, Y;
Myles, J;
Masegian, A;
... Wilkinson, RD; + view all
(2022)
Dark Energy Survey Year 3 Results: Measuring the Survey Transfer Function with Balrog.
Astrophysical Journal Supplement Series
, 258
(1)
, Article 15. 10.3847/1538-4365/ac26c1.
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Abstract
We describe an updated calibration and diagnostic framework, Balrog, used to directly sample the selection and photometric biases of the Dark Energy Survey (DES) Year 3 (Y3) data set. We systematically inject onto the single-epoch images of a random 20% subset of the DES footprint an ensemble of nearly 30 million realistic galaxy models derived from DES Deep Field observations. These augmented images are analyzed in parallel with the original data to automatically inherit measurement systematics that are often too difficult to capture with generative models. The resulting object catalog is a Monte Carlo sampling of the DES transfer function and is used as a powerful diagnostic and calibration tool for a variety of DES Y3 science, particularly for the calibration of the photometric redshifts of distant "source" galaxies and magnification biases of nearer "lens" galaxies. The recovered Balrog injections are shown to closely match the photometric property distributions of the Y3 GOLD catalog, particularly in color, and capture the number density fluctuations from observing conditions of the real data within 1% for a typical galaxy sample. We find that Y3 colors are extremely well calibrated, typically within ∼1–8 mmag, but for a small subset of objects, we detect significant magnitude biases correlated with large overestimates of the injected object size due to proximity effects and blending. We discuss approaches to extend the current methodology to capture more aspects of the transfer function and reach full coverage of the survey footprint for future analyses.
| Type: | Article |
|---|---|
| Title: | Dark Energy Survey Year 3 Results: Measuring the Survey Transfer Function with Balrog |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4365/ac26c1 |
| Publisher version: | https://doi.org/10.3847/1538-4365/ac26c1 |
| Language: | English |
| Additional information: | Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | Cosmology (343); Sky surveys (1464); Dark energy (351); Astronomical simulations (1857) |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10142563 |
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