Euclid preparation: X. The Euclid photometric-redshift challenge
Abstract
Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-z) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo-s at the required accuracy using only the broad-band photometry that those surveys will provide. An assessment of the strengths and weaknesses of current methods is a crucial step in the eventual development of an approach to meet this challenge. We report on the performance of 13 photometric redshift code single value redshift estimates and redshift probability distributions (PDZs) on a common set of data, focusing particularly on the 0.2--2.6 redshift range that the Euclid mission will probe. We design a challenge using emulated Euclid data drawn from three photometric surveys of the COSMOS field. The data are divided into two samples: one calibration sample for which photometry and redshifts are provided to the participants; and the validation sample, containing only the photometry, to ensure a blinded test of the methods. Participants were invited to provide a redshift single value estimate and a PDZ for each source in the validation sample, along with a rejection flag that indicates sources they consider unfit for use in cosmological analyses. The performance of each method is assessed through a set of informative metrics, using cross-matched spectroscopic and highly-accurate photometric redshifts as the ground truth. We show that the rejection criteria set by participants are efficient in removing strong outliers, sources for which the photo-z deviates by more than 0.15(1+z) from the spectroscopic-redshift (spec-z). We also show that, while all methods are able to provide reliable single value estimates, several machine-learning methods do not manage to produce useful PDZs. [abridged]
Cite
@article{arxiv.2009.12112,
title = {Euclid preparation: X. The Euclid photometric-redshift challenge},
author = {Euclid Collaboration and G. Desprez and S. Paltani and J. Coupon and I. Almosallam and A. Alvarez-Ayllon and V. Amaro and M. Brescia and M. Brodwin and S. Cavuoti and J. De Vicente-Albendea and S. Fotopoulou and P. W. Hatfield and W. G. Hartley and O. Ilbert and M. J. Jarvis and G. Longo and R. Saha and J. S. Speagle and A. Tramacere and M. Castellano and F. Dubath and A. Galametz and M. Kuemmel and C. Laigle and E. Merlin and J. J. Mohr and S. Pilo and M. Salvato and M. M. Rau and S. Andreon and N. Auricchio and C. Baccigalupi and A. Balaguera-Antolínez and M. Baldi and S. Bardelli and R. Bender and A. Biviano and C. Bodendorf and D. Bonino and E. Bozzo and E. Branchini and J. Brinchmann and C. Burigana and R. Cabanac and S. Camera and V. Capobianco and A. Cappi and C. Carbone and J. Carretero and C. S. Carvalho and R. Casas and S. Casas and F. J. Castander and G. Castignani and A. Cimatti and R. Cledassou and C. Colodro-Conde and G. Congedo and C. J. Conselice and L. Conversi and Y. Copin and L. Corcione and H. M. Courtois and J. -G. Cuby and A. Da Silva and S. de la Torre and H. Degaudenzi and D. Di Ferdinando and M. Douspis and C. A. J. Duncan and X. Dupac and A. Ealet and G. Fabbian and M. Fabricius and S. Farrens and P. G. Ferreira and F. Finelli and P. Fosalba and N. Fourmanoit and M. Frailis and E. Franceschi and M. Fumana and S. Galeotta and B. Garilli and W. Gillard and B. Gillis and C. Giocoli and G. Gozaliasl and J. Graciá-Carpio and F. Grupp and L. Guzzo and M. Hailey and S. V. H. Haugan and W. Holmes and F. Hormuth and A. Humphrey and K. Jahnke and E. Keihanen and S. Kermiche and M. Kilbinger and C. C. Kirkpatrick and T. D. Kitching and R. Kohley and B. Kubik and M. Kunz and H. Kurki-Suonio and S. Ligori and P. B. Lilje and I. Lloro and D. Maino and E. Maiorano and O. Marggraf and K. Markovic and N. Martinet and F. Marulli and R. Massey and M. Maturi and N. Mauri and S. Maurogordato and E. Medinaceli and S. Mei and M. Meneghetti and R. Benton Metcalf and G. Meylan and M. Moresco and L. Moscardini and E. Munari and S. Niemi and C. Padilla and F. Pasian and L. Patrizii and V. Pettorino and S. Pires and G. Polenta and M. Poncet and L. Popa and D. Potter and L. Pozzetti and F. Raison and A. Renzi and J. Rhodes and G. Riccio and E. Rossetti and R. Saglia and D. Sapone and P. Schneider and V. Scottez and A. Secroun and S. Serrano and C. Sirignano and G. Sirri and L. Stanco and D. Stern and F. Sureau and P. Tallada Crespí and D. Tavagnacco and A. N. Taylor and M. Tenti and I. Tereno and R. Toledo-Moreo and F. Torradeflot and L. Valenziano and J. Valiviita and T. Vassallo and M. Viel and Y. Wang and N. Welikala and L. Whittaker and A. Zacchei and G. Zamorani and J. Zoubian and E. Zucca},
journal= {arXiv preprint arXiv:2009.12112},
year = {2020}
}
Comments
Accepted in A&A, 25 pages, 13 figures, 7 tables