A1 Refereed original research article in a scientific journal
Euclid preparation: LXXVIII. Full-shape modelling of two-point and three-point correlation functions in real space
Authors: Guidi, M.; Veropalumbo, A.; Pugno, A.; Moresco, M.; Sefusatti, E.; Porciani, C.; Branchini, E.; Breton, M. -A.; Camacho Quevedo, B.; Crocce, M.; de la Torre, S.; Desjacques, V.; Eggemeier, A.; Farina, A.; Karcher, M.; Linde, D.; Marinucci, M.; Dizgah, A. Moradinezhad; Moretti, C.; Pardede, K.; Pezzotta, A.; Sarpa, E.; Amara, A.; Andreon, S.; Auricchio, N.; Baccigalupi, C.; Bagot, D.; Baldi, M.; Bardelli, S.; Battaglia, P.; Biviano, A.; Brescia, M.; Camera, S.; Canas-Herrera, G.; Capobianco, V.; Carbone, C.; Cardone, V. F.; Carretero, J.; Castellano, M.; Castignani, G.; Cavuoti, S.; Chambers, K. C.; Cimatti, A.; Colodro-Conde, C.; Congedo, G.; Conversi, L.; Copin, Y.; Courbin, F.; Courtois, H. M.; Da Silva, A.; Degaudenzi, H.; De Lucia, G.; Dole, H.; Douspis, M.; Dubath, F.; Dupac, X.; Dusini, S.; Escoffier, S.; Farina, M.; Farinelli, R.; Faustini, F.; Ferriol, S.; Finelli, F.; Fosalba, P.; Fotopoulou, S.; Frailis, M.; Franceschi, E.; Fumana, M.; Galeotta, S.; Gillis, B.; Giocoli, C.; Gracia-Carpio, J.; Grazian, A.; Grupp, F.; Guzzo, L.; Haugan, S. V. H.; Holmes, W.; Hormuth, F.; Hornstrup, A.; Jahnke, K.; Jhabvala, M.; Joachimi, B.; Keihanen, E.; Kermiche, S.; Kiessling, A.; Kubik, B.; Kummel, 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.; Markovic, K.; Martinelli, M.; Martinet, N.; Marulli, F.; Massey, R.; Medinaceli, E.; Mei, S.; Melchior, M.; Mellier, Y.; Meneghetti, M.; Merlin, E.; Meylan, G.; Mora, A.; Morin, B.; Moscardini, L.; Munari, E.; 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.; Sanchez, A. G.; Sapone, D.; Sartoris, B.; Schewtschenko, J. A.; Schneider, P.; Schrabback, T.; Scodeggio, M.; Secroun, A.; Seidel, G.; Seiffert, M.; Serrano, S.; Simon, P.; Sirignano, C.; Sirri, G.; Mancini, A. Spurio; Stanco, L.; Steinwagner, J.; Tallada-Crespi, P.; Tavagnacco, D.; Taylor, A. N.; Tereno, I.; Tessore, N.; Toft, S.; Toledo-Moreo, R.; Torradeflot, F.; Tsyganov, A.; Tutusaus, I.; Valenziano, L.; Valiviita, J.; Vassallo, T.; Kleijn, G. Verdoes; Wang, Y.; Weller, J.; Zamorani, G.; Zerbi, F. M.; Zucca, E.; Allevato, V.; Ballardini, M.; Bolzonella, M.; Bozzo, E.; Burigana, C.; Cabanac, R.; Calabrese, M.; Cappi, A.; Di Ferdinando, D.; Vigo, J. A. Escartin; Gabarra, L.; Martin-Fleitas, J.; Matthew, S.; Maturi, M.; Mauri, N.; Metcalf, R. B.; Nucita, A. A.; Pontinen, M.; Risso, I.; Scottez, V.; Sereno, M.; Tenti, M.; Viel, M.; Wiesmann, M.; Akrami, Y.; Andika, I. T.; Anselmi, S.; Archidiacono, M.; Atrio-Barandela, F.; Balaguera-Antolinez, A.; Bertacca, D.; Bethermin, M.; Blot, L.; Bohringer, H.; Borgani, S.; Brown, M. L.; Bruton, S.; Calabro, A.; Caro, F.; Carvalho, C. S.; Castro, T.; Cogato, F.; Conseil, S.; Contarini, S.; Cooray, A. R.; Cucciati, O.; Davini, S.; De Paolis, F.; Desprez, G.; Diaz-Sanchez, A.; Diaz, J. J.; Di Domizio, S.; Diego, J. M.; Dimauro, P.; Enia, A.; Fang, Y.; Ferrari, A. G.; Ferreira, P. G.; Finoguenov, A.; Franco, A.; Ganga, K.; Garcia-Bellido, J.; Gasparetto, T.; Gautard, V.; Gaztanaga, E.; Giacomini, F.; Gianotti, F.; Gozaliasl, G.; Gutierrez, C. M.; Hernandez-Monteagudo, C.; Hildebrandt, H.; Hjorth, J.; Joudaki, S.; Kajava, J. J. E.; Kang, Y.; Kansal, V.; Karagiannis, D.; Kiiveri, K.; Kirkpatrick, C. C.; Kruk, S.; Lattanzi, M.; Legrand, L.; Lembo, M.; Lepori, F.; Leroy, G.; Lesci, G. F.; Lesgourgues, J.; Leuzzi, L.; Liaudat, T. I.; Loureiro, A.; Macias-Perez, J.; Maggio, G.; Magliocchetti, M.; Mannucci, F.; Maoli, R.; Martins, C. J. A. P.; Maurin, L.; Miluzio, M.; Monaco, P.; Morgante, G.; Nadathur, S.; Naidoo, K.; Navarro-Alsina, A.; Nesseris, S.; Pagano, L.; Passalacqua, F.; Paterson, K.; Patrizii, L.; Pisani, A.; Potter, D.; Quai, S.; Radovich, M.; Reimberg, P.; Rocci, P. -F.; Rodighiero, G.; Sacquegna, S.; Sahlen, M.; Sanders, D. B.; Schneider, A.; Sciotti, D.; Sellentin, E.; Smith, L. C.; Sorce, J. G.; Tanidis, K.; Tao, C.; Testera, G.; Teyssier, R.; Tosi, S.; Troja, A.; Tucci, M.; Valieri, C.; Venhola, A.; Vergani, D.; Vernizzi, F.; Verza, G.; Vielzeuf, P.; Walton, N. A.; Euclid Collaboration
Publisher: EDP Sciences
Publication year: 2026
Journal: Astronomy and Astrophysics
Article number: A228
Volume: 707
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202556177
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Open Access publication channel
Web address : https://doi.org/10.1051/0004-6361/202556177
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/523283338
Self-archived copy's licence: CC BY
Self-archived copy's version: Publisher`s PDF
We investigated the accuracy and range of validity of the perturbative model for the two-point (2PCF) and three-point (3PCF) correlation functions in real space in view of the forthcoming analysis of the Euclid mission spectroscopic sample. We took advantage of clustering measurements from four snapshots of the Flagship I N-body simulations at z = {0.9, 1.2, 1.5, 1.8}, which mimic the expected galaxy population in the ideal case, i.e. in the absence of observational effects such as purity and completeness. For the 3PCF we considered all available triangular configurations given a minimal separation (r(min)). We first assessed the model performance by fixing the cosmological parameters and evaluating the goodness of fit provided by the perturbative bias expansion in the joint analysis of the two statistics, finding an overall agreement with the data down to separations of 20 h(-1) Mpc. Subsequently, we built on the state-of-the-art analysis and extended it to include the dependence on three cosmological parameters: the amplitude of scalar perturbations (A(s)), the matter density (omega(cdm)), and the Hubble parameter (h). To achieve this goal, we developed an emulator capable of generating fast and robust modelling predictions for the two summary statistics, which thus enables an efficient sampling of the joint likelihood function. We therefore present the first joint full-shape analysis of the real-space 2PCF and 3PCF, testing the consistency and constraining power of the perturbative model across both probes and assessing its performance in a combined likelihood framework. We explored possible systematic uncertainties induced by the perturbative model at small scales, finding an optimal scale cut of r(min) = 30 h(-1) Mpc for the 3PCF when imposing an additional limitation on the nearly isosceles triangular configurations included in the data vector. This work is part of a series of papers in which we validate theoretical models for galaxy clustering measurements in preparation for the Euclid mission.
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Funding information in the publication:
We thank Krister Nagainis, Adi Nusser and Andrea Enia for useful discussions. MG and MM acknowledge support from the research grant 'Optimizing the extraction of cosmological information from Large Scale Structure analysis in view of the next large spectroscopic surveys' from MIUR, PRIN 2022 (grant 2022NY2ZRS 001). MM acknowledges the financial contribution from the grant ASI n. 2024-10-HH.0 "Attivita scientifiche per la missione Euclid - fase E. 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 Forschungsforderungsgesellschaft funded through BMK, the Belgian Science Policy, the Canadian Euclid Consortium, the Deutsches Zentrum fur Luft- und Raumfahrt, the DTU Space and the Niels Bohr Institute in Denmark, the French Centre National d'Etudes Spatiales, the Fundacao para a Ciencia e a Tecnologia, the Hungarian Academy of Sciences, the Ministerio de Ciencia, Innovacion 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).
