We present initial results from the Dark Energy Spectroscopic Instrument (DESI) Complete Calibration of the Color-Redshift Relation (DC3R2) secondary target survey. Our analysis uses 230k galaxies that overlap with KiDS-VIKING ugriZYJHKs photometry to calibrate the color-redshift relation and to inform photometric redshift (photo-z) inference methods of future weak lensing surveys. Together with Emission Line Galaxies (ELGs), Luminous Red Galaxies (LRGs), and the Bright Galaxy Survey (BGS) that provide samples of complementary color, the DC3R2 targets help DESI to span 56% of the color space visible to Euclid and LSST with high confidence spectroscopic redshifts. The effects of spectroscopic completeness and quality are explored, as well as systematic uncertainties introduced with the use of common Self Organizing Maps trained on different photometry than the analysis sample. We further examine the dependence of redshift on magnitude at fixed color, important for the use of bright galaxy spectra to calibrate redshifts in a fainter photometric galaxy sample. We find that noise in the KiDS-VIKING photometry introduces a dominant, apparent magnitude dependence of redshift at fixed color, which indicates a need for carefully chosen deep drilling fields, and survey simulation to model this effect for future weak lensing surveys.
@article{arxiv.2309.13109,
title = {DESI Complete Calibration of the Color-Redshift Relation (DC3R2): Results from early DESI data},
author = {J. McCullough and D. Gruen and A. Amon and A. Roodman and D. Masters and A. Raichoor and D. Schlegel and R. Canning and F. J. Castander and J. DeRose and R. Miquel and J. Myles and J. A. Newman and A. Slosar and J. Speagle and M. J. Wilson and J. Aguilar and S. Ahlen and S. Bailey and D. Brooks and T. Claybaugh and S. Cole and K. Dawson and A. de la Macorra and P. Doel and J. E. Forero-Romero and S. Gontcho A Gontcho and J. Guy and R. Kehoe and A. Kremin and M. Landriau and L. Le Guillou and M. Levi and M. Manera and P. Martini and A. Meisner and J. Moustakas and J. Nie and W. J. Percival and C. Poppett and F. Prada and M. Rezaie and G. Rossi and E. Sanchez and H. Seo and G. Tarlé and B. A. Weaver and Z. Zhou and H. Zou},
journal= {arXiv preprint arXiv:2309.13109},
year = {2024}
}
Comments
19 pages, 16 figures, published in MNRAS, interactive visualizations at https://jmccull.github.io/DC3R2_Overview