Euclid Quick Data Release (Q1). Characteristics and limitations of the spectroscopic measurements

The spectroscopy processing function (SPE PF) of the Euclid pipeline is dedicated to the automatic analysis of 1D spectra to determine redshifts, line fluxes, and spectral classifications. The first Euclid Quick Data Release (Q1) delivers these measurements for all ̋E<22.5 objects identified in the photometric survey. In this paper, we present an overview of the SPE PF algorithm and assess its performance by comparing its results with high-quality spectroscopic redshifts from the Dark Energy Spectroscopic Instrument (DESI) survey in the Euclid Deep Field North. Our findings highlight remarkable accuracy in successful redshift measurements, with a bias of less than $3 $ in $(z_ ̊m SPE -z_ ̊m DESI )/(1+z_ ̊m DESI )$ and a high precision of approximately 10^-3. The majority of spectra have only a single spectral feature or none at all. To avoid spurious detections, whereby noise features are misinterpreted as lines or lines are misidentified, it is therefore essential to apply well-defined criteria on quantities such as the redshift probability, or the flux, and signal-to-noise ratio. Using a well-tuned quality selection, we achieve an 89% redshift success rate in the target redshift range for cosmology ($0.9<z<1.8$), which is well covered by DESI for z<1.6. Outside this range in which the line is observable, redshift measurements are less reliable, except for sources showing specific spectral features (e.g. two bright lines or strong continuum). The classification based on spectroscopy alone is effective for galaxies (about 80% success rate), while it is less efficient for stars and quasars ($<60%$). Ongoing refinements along the entire chain of PFs are expected to enhance both redshift measurements and spectral classification, allowing us to define the large and reliable sample required for cosmological analyses. Taking into account the planned evolution of the spectroscopic pipeline, partially based on the limitations identified in this paper, these results are encouraging for Euclid's future galaxy clustering measurements, even though the requirements are not yet fulfilled.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-10-28
DOI
https://doi.org/10.1051/0004-6361/202554607
Citations
3
Primary Topic
Spectroscopy and Laser Applications
Type
article
Field-Weighted Citation Impact
2.27

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Euclid Quick Data Release (Q1). Characteristics and limitations of the spectroscopic measurements

M Viel, D Sapone, S Pires, J. Brinchmann et al.
3 citations
Astronomy and Astrophysics
Spectroscopy and Laser Applications
2.27
article

Euclid Quick Data Release (Q1). Characteristics and limitations of the spectroscopic measurements

M Viel, D Sapone, S Pires, J. Brinchmann, F Passalacqua, S Casas, Will J. Percival, M. Ballardini, Pierre-Yves Chabaud, E.A Magnier, P. Tallada-Crespí, S Sacquegna, S Matthew, L. Conversi, A. Pisani, D. Le Mignant, M. Brescia, I Tereno, E. Merlin, G de Lucia, R Nakajima, B. Joachimi, M Kümmel, W.G Hartley, S Bardelli, J. Steinwagner, C. Surace, D. B. Sanders, F. Marulli, A.G Ferrari, H Hildebrandt, Yunting Fang, Nuria Mauri, S Ferriol, C. Giocoli, G Zamorani, L Patrizii, K Kiiveri, J. F. Macías–Pérez, Paola Dimauro, F. Courbin, S Dusini, Pietro Battaglia, M Baldi, A. Kiessling, Michael D. Brown, F. Torradeflot, Elena Sellentin, A. Díaz‐Sánchez, E Maiorano, J.J Diaz, G. Gozaliasl, S Nadathur, S. Mei, G. Desprez, F Faustini, A Montoro, Francisco Javier Castander, Daniele Bertacca, M. Radovich, A. Finoguenov, M. Magliocchetti, Alberto Basset, V. Capobianco, Q Le Boulc'H, Laura Leuzzi, L. Moscardini, S.-M Niemi, T. Schrabback, Santiago Avila, S.J Liu, L. Gabarra, M Miluzio, M Maturi, C. J. A. P. Martins, B Altieri, S. Andreon, M. Schirmer, S. V. H. Haugan, R. Massey, S Marcin, T. Vassallo, A Troja, S. Paltani, Valérie Gautard, R. Toledo-Moreo, Alvaro E. Cordero-Franco, B. Camacho Quevedo, J. Hoar, S Bruton, M. Moresco, G Seidel, A Navarro-Alsina, B. R. Granett, K George, M. Meneghetti, D. Bonino, G. Testera, J.W Nightingale, J. J. E. Kajava, F Grupp, X Dupac, M. Poncet, A. Cappi, T.I Liaudat, S Toft, Marine Ruffenach, K. Ganga, Simon Conseil, A. Caillat, N Tessore, B Gillis, C. Mancini, E. Romelli, C. Burigana, A. M. Di Giorgio, L Stanco, S Quai, Henk Hoekstra, A. Biviano, I. Tutusaus, H. Degaudenzi, I.A Zinchenko, N. Martinet, I Risso, K Paterson, V. Allevato, J. Väliviita, D. Vibert, C Sirignano, W. Gillard, J. Carretero, John A. Peacock, D. Karagiannis, S. Escoffier, C. Padilla Aranda, K. Pedersen, L Blot, Maria Lembo, D. Vergani, M Sahlén, M. Roncarelli, F. Dubath, F. De Paolis, Jenny G. Sorce, R. B. Metcalf, A. Hornstrup, E. Medinaceli, Sandor Kruk, M. Pöntinen, S. Di Domizio, Maximilian Fabricius, Francesco Shankar, R. B. Metcalf, F. M. Zerbi, M. Béthermin, A. Balestra, K. Jahnkę, E. Branchini, A. M. N. Ferguson, A. Secroun, M. Farina, F. Mannucci, M Jhabvala, F. Pasian, A. Venhola, L. Guzzo, V. Kansal, S Anselmi, J. Weller, S Borgani, Sameer Alvi, S. Ligori, F Lepori, F. Giacomini, L Zalesky, J. Rhodes, S. Galeotta, J. Hjorth, F. Raison, J.R Weaver, A Amara, E. Franceschi, A. Fontana, P. Bergamini, J.A Schewtschenko, Abdelhamid Allaoui, ENRIQUE GAZTAÑAGA, P.‐A. Duc, J Martín-Fleitas, R. Farinelli, T Castro, N. A. Walton, R Saglia, C. Giocoli, Y Charles, G Cañas-Herrera, J. Gracia-Carpio, I.T Andika, R. Cabanac, Savvas Nesseris, R Teyssier, Z. Sakr, K Tanidis, L. Legrand, E. Bozzo, LAURENCE C. SMITH, G.F Lesci, Asantha Cooray, K. C. Chambers, M. Archidiacono, T Gasparetto, V. Lindholm, M. Sauvage, W. M. Holmes, R. Rébolo, G. Verdoes Kleijn, R Farinelli, P.-F Rocci, A Grazian, E. Keihänen, B. Sartoris, G. Castignani, P Vielzeuf, P. C. Schneider, G D'aste, M. Martinelli, Krishna Naidoo, A da Silva, N. Auricchio, M. Frailis, V Scottez, M. Fumana, Jean-Gabriel Cuby, Ranga‐Ram Chary, S Camera, Yongshui Kang, C. Carbone, Zijun Mao, S. Kermiche, H.I Teplitz, Arthur Loureiro, F Caro, E Sarpa, J. M. Diego, G Sirri, O. Mansutti, Rafael Giménez, Claudia Scarlata, P. B. Lilje, M. Scodeggio, Chiara Moretti, E. Palazzi, M Melchior, Giulio Fabbian, A Veropalumbo, C.S. Carvalho, M. Talia, L.A. Popa, E. Rossetti, A Renzi, A Pezzotta, O Marggraf, Araceli Mora Enguídanos, A.M.C Le Brun, Aurel Schneider, Giuseppe Riccio, I Lloro, M. Douspis, C. Porciani, S Cavuoti, Y. Akrami, F. Atrio‐Barandela, H. M. Courtois, R. C. Nichol, F. Cogato, D Sciotti, P Casenove, K. Jahnkę, F Dufresne, S. Tosi, Andrew Hall, L. Maurin, C. M. Gutiérrez, M Kunz, M Bolzonella, Y. Mellier, C Neissner, Margaret E. Sereno, V. Le Brun, M. Tenti, C.C Kirkpatrick, D. Di Ferdinando, J García-Bellido, S. de la Torre, V. Pettorino, G Congedo, A Calabro, G Morgante, O Cucciati, G Polenta, H. Kurki‐Suonio, P. Hudelot, S. Davini, M. Wiesmann, C. Hernández-Monteagudo, A. Ealet, N. Aghanim, H. Dole, C. Baccigalupi, S. Maurogordato, F. Hormuth, A. N. Taylor, J.A. Escartin Vigo, A. Cimatti, B. Kubik, G Mainetti, P Monaco, G. Meylan, M. Seiffert, M Tucci, S. Fotopoulou, N. Fourmanoit, M. Bella, G Verza, L Valenziano, F. Gianotti, M. N. Bremer, C Valieri, Mary W. Gray, T. Vassallo, A. Costille, J. Lesgourgues, M Guidi, E Zucca, D Potter, C.J Conselice, A. Gregorio, Yang Wang, T Bedrine, D Bagot
article en
3 citations

Abstract

The spectroscopy processing function (SPE PF) of the Euclid pipeline is dedicated to the automatic analysis of 1D spectra to determine redshifts, line fluxes, and spectral classifications. The first Euclid Quick Data Release (Q1) delivers these measurements for all ̋E<22.5 objects identified in the photometric survey. In this paper, we present an overview of the SPE PF algorithm and assess its performance by comparing its results with high-quality spectroscopic redshifts from the Dark Energy Spectroscopic Instrument (DESI) survey in the Euclid Deep Field North. Our findings highlight remarkable accuracy in successful redshift measurements, with a bias of less than $3 $ in $(z_ ̊m SPE -z_ ̊m DESI )/(1+z_ ̊m DESI )$ and a high precision of approximately 10^-3. The majority of spectra have only a single spectral feature or none at all. To avoid spurious detections, whereby noise features are misinterpreted as lines or lines are misidentified, it is therefore essential to apply well-defined criteria on quantities such as the redshift probability, or the flux, and signal-to-noise ratio. Using a well-tuned quality selection, we achieve an 89% redshift success rate in the target redshift range for cosmology ($0.9<z<1.8$), which is well covered by DESI for z<1.6. Outside this range in which the line is observable, redshift measurements are less reliable, except for sources showing specific spectral features (e.g. two bright lines or strong continuum). The classification based on spectroscopy alone is effective for galaxies (about 80% success rate), while it is less efficient for stars and quasars ($<60%$). Ongoing refinements along the entire chain of PFs are expected to enhance both redshift measurements and spectral classification, allowing us to define the large and reliable sample required for cosmological analyses. Taking into account the planned evolution of the spectroscopic pipeline, partially based on the limitations identified in this paper, these results are encouraging for Euclid's future galaxy clustering measurements, even though the requirements are not yet fulfilled.

Astronomy and Astrophysics
Université Paris Cité (FR), Université de Lille (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Centre National d'Études Spatiales (FR), Institut d'Astrophysique de Paris (FR), European Space Agency (FR), Laboratoire AstroParticule et Cosmologie (FR), Observatoire astronomique de Strasbourg (FR), CEA Grenoble (FR), Astrophysique, Instrumentation et Modélisation (FR), Janssen (France) (FR), Laboratoire Univers et Théories (FR), Centre de physique des particules de Marseille (FR), Laboratoire d’Astrophysique de Marseille (FR), Institut d'Astrophysique Spatiale (FR), CEA Cadarache (FR), Lagrange Laboratory (FR), Château Gombert (FR), CEA Paris-Saclay (FR), Laboratoire de Physique Subatomique et de Cosmologie (FR), Centre de Calcul de l’Institut National de Physique Nucléaire et de Physique des Particules (FR), Institute of Nuclear Physics of Lyon (FR), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), Institut de Recherche en Astrophysique et Planétologie (FR), Institut de Physique des 2 Infinis de Lyon (FR)
National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Ministerio de Ciencia, Innovación y Universidades, European Space Agency, Consejo Nacional de Ciencia y Tecnología, Magyar Tudományos Akadémia, Agenzia Spaziale Italiana, Ministerio de Ciencia e Innovación, National Astronomical Observatory of Japan, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Agenția Spațială Română, Norsk Romsenter, Office of Science, Science and Technology Facilities Council, Fundação para a Ciência e a Tecnologia, Division of Astronomical Sciences, Lawrence Berkeley National Laboratory
Openalex Percentile: Top 11%
Spectroscopy and Laser Applications
2.27
DOIOpen Access PDFOpenAlex
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