Euclid preparation. LXXXII. Predicting star-forming galaxy scaling relations with the spectral stacking code SpectraPyle

Euclid Collaboration; Quai, S.; Pozzetti, L.; Talia, M.; Mancini, C.; Cassata, P.; Gabarra, L.; Le Brun, V.; Bolzonella, M.; Rossetti, E.; Kruk, S.; Granett, B. R.; Scarlata, C.; Moresco, M.; Zamorani, G.; Mao, Z.; Vergani, D.; Lopez Lopez, X.; Enia, A.; Daddi, E.; Allevato, V.; Zinchenko, I. A.; Magliocchetti, M.; Siudek, M.; Bisigello, L.; De Lucia, G.; Dickinson, H. J.; Lusso, E.; Hirschmann, M.; Cimatti, A.; Wang, L.; Sorce, J. G.; Huertas-Company, M.; Aghanim, N.; Amara, A.; Andreon, S.; Auricchio, N.; Baccigalupi, C.; Baldi, M.; Bardelli, S.; Biviano, A.; Branchini, E.; Brescia, M.; Brinchmann, J.; Camera, S.; Cañas-Herrera, G.; Capobianco, V.; Carbone, C.; Carretero, J.; Casas, S.; Castellano, M.; Castignani, G.; Cavuoti, S.; Chambers, K. C.; Colodro-Conde, C.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Courbin, F.; Courtois, H. M.; Da Silva, A.; Degaudenzi, H.; de la Torre, S.; Dole, H.; Douspis, M.; Dubath, F.; Dupac, X.; Dusini, S.; Ealet, A.; Escoffier, S.; Farina, M.; Farinelli, R.; Faustini, F.; Ferriol, S.; Finelli, F.; Fourmanoit, N.; Frailis, M.; Franceschi, E.; Galeotta, S.; George, K.; Gillard, W.; Gillis, B.; Giocoli, C.; Gracia-Carpio, J.; Grazian, A.; Grupp, F.; Guzzo, L.; Haugan, S. V. H.; Holmes, W.; Hook, I. M.; Hormuth, F.; Hornstrup, A.; Hudelot, P.; Jahnke, K.; Jhabvala, M.; Joachimi, B.; Keihänen, E.; Kermiche, S.; Kiessling, A.; Kubik, B.; Kümmel, M.; Kunz, M.; Kurki-Suonio, H.; Le Brun, A. M. C.; Ligori, S.; Lilje, P. B.; Lindholm, V.; Lloro, I.; Mainetti, G.; Maino, D.; Maiorano, E.; Mansutti, O.; Marcin, S.; Marggraf, O.; Martinelli, M.; Martinet, N.; Marulli, F.; Massey, R. J.; Medinaceli, E.; Mei, S.; Melchior, M.; Mellier, Y.; Meneghetti, M.; Merlin, E.; Meylan, G.; Mora, A.; Moscardini, L.; Neissner, C.; Niemi, S.-M.; Padilla, C.; Paltani, S.; Pasian, F.; Pedersen, K.; Percival, W. J.; Pettorino, V.; Pires, S.; Polenta, G.; Poncet, M.; Popa, L. A.; Raison, F.; Rebolo, R.; Renzi, A.; Rhodes, J.; Riccio, G.; Romelli, E.; Roncarelli, M.; Saglia, R.; Sakr, Z.; Sánchez, A. G.; Sapone, D.; Sartoris, B.; Schneider, P.; Schrabback, T.; Scodeggio, M.; Secroun, A.; Sefusatti, E.; Seidel, G.; Seiffert, M.; Serrano, S.; Simon, P.; Sirignano, C.; Sirri, G.; Stanco, L.; Starck, J.-L.; Steinwagner, J.; Tallada-Crespí, P.; Tavagnacco, D.; Taylor, A. N.; Teplitz, H. I.; Tereno, I.; Toft, S.; Toledo-Moreo, R.; Torradeflot, F.; Tutusaus, I.; Valenziano, L.; Valiviita, J.; Vassallo, T.; Verdoes Kleijn, G.; Veropalumbo, A.; Vibert, D.; Wang, Y.; Weller, J.; Zucca, E.; Ballardini, M.; Bozzo, E.; Burigana, C.; Cabanac, R.; Cappi, A.; Di Ferdinando, D.; Escartin Vigo, J. A.; Martín-Fleitas, J.; Matthew, S.; Mauri, N.; Metcalf, B. R.; Pezzotta, A.; Pöntinen, M.; Porciani, C.; Risso, I.; Scottez, V.; Sereno, M.; Tenti, M.; Viel, M.; Wiesmann, M.; Akrami, Y.; Andika, I. T.; Anselmi, S.; Archidiacono, M.; Atrio-Barandela, F.; Bergamini, P.; Bertacca, D.; Bethermin, M.; Blanchard, A.; Blot, L.; Borgani, S.; Brown, M. L.; Bruton, S.; Calabro, A.; Camacho Quevedo, B.; Caro, F.; Carvalho, C. S.; Castro, T.; Cogato, F.; Conseil, S.; Contini, T.; Cooray, A. R.; Cucciati, O.; Davini, S.; Desprez, G.; Díaz-Sánchez, A.; Diaz, J. J.; Di Domizio, S.; Diego, J. M.; Fang, Y.; Ferrari, A. G.; Finoguenov, A.; Fontana, A.; Fontanot, F.; Franco, A.; Ganga, K.; García-Bellido, J.; Gasparetto, T.; Gautard, V.; Gaztanaga, E.; Giacomini, F.; Gianotti, F.; Gozaliasl, G.; Guidi, M.; Gutierrez, C. M.; Hall, A.; Hemmati, S.; Hernández-Monteagudo, C.; Hildebrandt, H.; Hjorth, J.; Kajava, J. J. E.; Kang, Y.; Kansal, V.; Karagiannis, D.; Kiiveri, K.; Kirkpatrick, C. C.; Legrand, L.; Lembo, M.; Lepori, F.; Leroy, G.; Lesci, G. F.; Lesgourgues, J.; Leuzzi, L.; Liaudat, T. I.; Liu, S. J.; Loureiro, A.; Macias-Perez, J.; Maggio, G.; Mannucci, F.; Maoli, R.; Martins, C. J. A. P.; Maurin, L.; Miluzio, M.; Monaco, P.; Moretti, C.; Morgante, G.; Nadathur, S.; Naidoo, K.; Navarro-Alsina, A.; Nesseris, S.; Passalacqua, F.; Paterson, K.; Patrizii, L.; Pisani, A.; Potter, D.; Radovich, M.; Rocci, P.-F.; Rodighiero, G.; Sacquegna, S.; Sahlén, M.; Sanders, D. B.; Sarpa, E.; Schneider, A.; Sciotti, D.; Sellentin, E.; Shankar, F.; Smith, L. C.; Tanidis, K.; Tao, C.; Testera, G.; Teyssier, R.; Tosi, S.; Troja, A.; Tucci, M.; Valieri, C.; Venhola, A.; Verza, G.; Vielzeuf, P.; Walton, N. A.

doi:10.1051/0004-6361/202557329

Published March 2026 | Version Published

Journal Article Open

Euclid preparation. LXXXII. Predicting star-forming galaxy scaling relations with the spectral stacking code SpectraPyle

1. University of Bologna
2. INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129, Bologna, Italy
3. Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
4. University of Padua
5. Osservatorio Astronomico di Padova
6. University of Oxford
7. French National Centre for Scientific Research
8. European Space Astronomy Centre
9. Brera Astronomical Observatory
10. University of Minnesota
11. University of Paris
12. Astronomical Observatory of Capodimonte
13. Ludwig-Maximilians-Universität München
14. Institute for Space Astrophysics and Planetology
15. Instituto de Astrofísica de Canarias
16. University of La Laguna
17. Institute of Space Sciences
18. Trieste Astronomical Observatory
19. The Open University
20. Arcetri Astrophysical Observatory
21. University of Florence
22. École Polytechnique Fédérale de Lausanne
23. Netherlands Institute for Space Research
24. University of Groningen
25. University of Lille
26. Institut d'Astrophysique Spatiale
27. Sorbonne University
28. University of Surrey
29. Institute for Fundamental Physics of the Universe
30. INFN Sezione di Trieste
31. International School for Advanced Studies
32. INFN Sezione di Bologna
33. University of Genoa
34. INFN Sezione di Genova
35. University of Naples Federico II
36. University of Porto
37. European Southern Observatory
38. University of Turin
39. INFN Sezione di Torino
40. Osservatorio Astrofisico di Torino
41. European Space Research and Technology Centre
42. Leiden University
43. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
44. Port d'Informació Científica
45. RWTH Aachen University
46. Astronomical Observatory of Rome
47. INFN Sezione di Napoli
48. University of Hawaii at Manoa
49. University of Edinburgh
50. University of Manchester
51. European Space Research Institute
52. Claude Bernard University Lyon 1
53. University of Barcelona
54. Institució Catalana de Recerca i Estudis Avançats
55. UCB Lyon 1, CNRS/IN2P3, IUF, IP2I Lyon, 4 rue Enrico Fermi, 69622, Villeurbanne, France
56. University of Lisbon
57. University of Geneva
58. INFN Sezione di Padova
59. Center for Particle Physics of Marseilles
60. Agenzia Spaziale Italiana
61. Max Planck Institute for Extraterrestrial Physics
62. University of Milan
63. INFN Sezione di Milano
64. University of Oslo
65. Jet Propulsion Lab
66. Lancaster University
67. Felix Hormuth Engineering, Goethestr. 17, 69181, Leimen, Germany
68. Technical University of Denmark
69. University of Copenhagen
70. Institut d'Astrophysique de Paris
71. Max Planck Institute for Astronomy
72. Goddard Space Flight Center
73. University College London
74. University of Helsinki
75. Helsinki Institute of Physics
76. Square Kilometre Array Organisation
77. Centre de Calcul de l'Institut National de Physique Nucléaire et de Physique des Particules
78. University of Applied Sciences and Arts Northwestern Switzerland
79. University of Bonn
80. INFN Sezione di Roma I
81. Durham University
82. Astroparticle and Cosmology Laboratory
83. CNRS-UCB International Research Laboratory, Centre Pierre Binétruy, IRL2007, CPB-IN2P3, Berkeley, USA
84. Telespazio UK S.L. for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo Villanueva de la Cañada, 28692, Madrid, Spain
85. Institute for High Energy Physics
86. University of Waterloo
87. Perimeter Institute
88. Centre National d'Études Spatiales
89. Institute of Space Science
90. Spanish National Research Council
91. Heidelberg University
92. Research Institute in Astrophysics and Planetology
93. Université St Joseph; Faculty of Sciences, Beirut, Lebanon
94. University of Chile
95. Universität Innsbruck
96. Institut d'Estudis Espacials de Catalunya
97. Satlantis, University Science Park, Sede Bld 48940, Leioa-Bilbao, Spain
98. Infrared Processing and Analysis Center
99. Cosmic Dawn Center (DAWN)
100. Polytechnic University of Cartagena
101. University of Ferrara
102. INFN Sezione di Ferrara
103. Istituto di Radioastronomia di Bologna
104. Observatoire de la Côte d'Azur
105. Lagrange Laboratory
106. Aurora Technology for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692, Madrid, Spain
107. Groupe Institut supérieur d'agriculture de Lille
108. ICSC – Centro Nazionale di Ricerca in High Performance Computing, Big Data e Quantum Computing, Via Magnanelli 2, Bologna, Italy
109. Institute for Theoretical Physics
110. Case Western Reserve University
111. Technical University of Munich
112. Max Planck Institute for Astrophysics
113. University of Salamanca
114. Observatory of Strasbourg
115. University of Tokyo
116. University of Trieste
117. California Institute of Technology
118. University of California, Irvine
119. Institute of Physics of Cantabria
120. INFN Sezione di Lecce
121. University of Salento
122. INAF-Sezione di Lecce, c/o Dipartimento Matematica e Fisica, Via per Arnesano, 73100, Lecce, Italy
123. CEA Saclay
124. University of Portsmouth
125. Aalto University
126. Ruhr University Bochum
127. University of Turku
128. Serco for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo, Villanueva de la Cañada, 28692, Madrid, Spain
129. ARC Centre of Excellence for Dark Matter Particle Physics
130. Swinburne University of Technology
131. University of the Western Cape
132. University of Cambridge
133. University of Zurich
134. Institut de Recherche sur les Lois Fondamentales de l'Univers
135. Stockholm University
136. Imperial College London
137. Grenoble Institute of Technology
138. Sapienza University of Rome
139. Centre for Astrophysics of the University of Porto
140. HE Space for European Space Agency (ESA), Camino bajo del Castillo, s/n, Urbanizacion Villafranca del Castillo Villanueva de la Cañada, 28692, Madrid, Spain
141. Collurania Teramo Observatory
142. Uppsala University
143. University of Southampton
144. Princeton University
145. University of Oulu
146. Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, 10010, New York, NY, USA

We introduce SpectraPyle, a versatile spectral stacking pipeline developed for the Euclid mission’s NISP spectroscopic surveys, aimed at extracting faint emission lines and spectral features from large galaxy samples in the Wide and Deep Surveys. Designed for computational efficiency and flexible configuration, SpectraPyle supports the processing of extensive datasets critical to Euclid’s non-cosmological science goals. We validated the pipeline using simulated spectra processed to match Euclid’s expected final data quality. Stacking enables robust recovery of key emission lines, including Hα, Hβ, [O III], and [N II], below individual detection limits. However, the measurement of galaxy properties such as star formation rate, dust attenuation, and gas-phase metallicity are biased at stellar mass below log₁₀(M_/ M_⊙)∼9 due to the flux-limited nature of Euclid spectroscopic samples, where spectra below the detection threshold lack reliable redshift measurements, preventing effective stacking. The star formation rate–stellar mass relation of the parent sample is recovered reliably only in the deep survey for log₁₀(M_/ M_⊙)≳10, whereas the metallicity–mass relation is recovered more accurately over a wider mass range. These limitations are caused by the increased fraction of redshift measurement errors at lower masses and fluxes. We examined the impact of residual redshift contaminants that arises from mis-identified emission lines and noise spikes, on stacked spectra. Even after stringent quality selections, low-level contamination (< 6%) has minimal impact on line fluxes due to the systematically weaker emission of contaminants. A percentile-based analysis of stacked spectra provides a sensitive diagnostic for detecting contamination via coherent spurious features at characteristic wavelengths. While our simulations include most instrumental effects, real Euclid data will require a further refinement of contamination mitigation strategies.

Copyright and License

© The Authors 2026. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

The Euclid Consortium acknowledges the European Space Agency and a number of agencies and institutes that have supported the development of Euclid, in particular the Agenzia Spaziale Italiana, the Austrian Forschungsförderungsgesellschaft funded through BMIMI, the Belgian Science Policy, the Canadian Euclid Consortium, the Deutsches Zentrum für Luft- und Raumfahrt, the DTU Space and the Niels Bohr Institute in Denmark, the French Centre National d’Etudes Spatiales, the Fundação para a Ciência e a Tecnologia, the Hungarian Academy of Sciences, the Ministerio de Ciencia, Innovación y Universidades, the National Aeronautics and Space Administration, the National Astronomical Observatory of Japan, the Netherlandse Onderzoekschool Voor Astronomie, the Norwegian Space Agency, the Research Council of Finland, the Romanian Space Agency, the State Secretariat for Education, Research, and Innovation (SERI) at the Swiss Space Office (SSO), and the United Kingdom Space Agency. A complete and detailed list is available on the Euclid web site (www.euclid-ec.org). S.Q., L.P., M.T., B.G., A.E., E.D., V.A., G.D.L., H.D. acknowledge support from the ELSA project. ‘ELSA: Euclid Legacy Science Advanced analysis tools’ (Grant Agreement no. 101135203) is funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or Innovate UK. Neither the European Union nor the granting authority can be held responsible for them. UK participation is funded through the UK HORIZON guarantee scheme under Innovate UK grant 10093177. V.A. and E.L. acknowledge the support from the INAF Large Grant ‘AGN & Euclid: a close entanglement’ Ob. Fu. 01.05.23.01.14. C.S. acknowledges the support of NASA ROSES Grant 12-EUCLID11-0004 M.S. acknowledges support by the State Research Agency of the Spanish Ministry of Science and Innovation under the grants ‘Galaxy Evolution with Artificial Intelligence’ (PGC2018-100852-A-I00) and ‘BASALT’ (PID2021-126838NB-I00) and the Polish National Agency for Academic Exchange (Bekker grant BPN/BEK/2021/1/00298/DEC/1). This work was partially supported by the European Union’s Horizon 2020 Research and Innovation program under the Maria Sklodowska-Curie grant agreement (No. 754510). L.R. acknowledges support from the Next Generation EU funds within the National Recovery and Resilience Plan (PNRR), Mission 4 – Education and Research, Component 2 – From Research to Business (M4C2), Investment Line 3.1 – Strengthening and creation of Research Infrastructures, Project IR0000034 – “STILES - Strengthening the Italian Leadership in ELT and SKA”.

Files

aa57329-25.pdf

Files (4.9 MB)

Name	Size
aa57329-25.pdf md5:bd49ef660d3735b46c3f0ac68e215902	4.9 MB	Preview Download

Additional details

Is new version of: Discussion Paper: arXiv:2509.16120 (arXiv)

European Space Agency
European Union
101135203
European Union
10093177
National Institute for Astrophysics
01.05.23.01.14
National Aeronautics and Space Administration
ROSES 12-EUCLID11-0004
Ministerio de Ciencia, Innovación y Universidades
PGC2018-100852-A-I00
Ministerio de Ciencia, Innovación y Universidades
PID2021-126838NB-I00
Narodowa Agencja Wymiany Akademickiej
BPN/BEK/2021/1/00298/DEC/1
European Research Council
754510

Available: 2026-03-17

Published online

Caltech groups: Division of Physics, Mathematics and Astronomy (PMA) , Infrared Processing and Analysis Center (IPAC)
Publication Status: Published

	All versions	This version
Views	95	95
Downloads	39	39
Data volume	209.7 MB	209.7 MB

Euclid preparation. LXXXII. Predicting star-forming galaxy scaling relations with the spectral stacking code SpectraPyle

Copyright and License

Acknowledgement

Files

aa57329-25.pdf

Files (4.9 MB)

Additional details

Related works

Funding

Dates

Caltech Custom Metadata

Euclid preparation. LXXXII. Predicting star-forming galaxy scaling relations with the spectral stacking code SpectraPyle

Creators

Abstract

Copyright and License

Acknowledgement

Files

aa57329-25.pdf

Files (4.9 MB)

Additional details

Related works

Funding

Dates

Caltech Custom Metadata