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Euclid: Field-level inference of primordial non-Gaussianity and cosmic initial conditions

Lookup NU author(s): James NightingaleORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© The Authors 2026. Open Access article, https://www.edpsciences.org, 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.This article is published in open access under the https://www.aanda.org/subscribe-to-open-faqs. mailto:subscribers@edpsciences.org to support open access publication. A primary target of the Euclid space mission is to constrain early-universe physics by searching for deviations from a primordial Gaussian random field. A significant detection of primordial non-Gaussianity would rule out the simplest models of cosmic inflation and transform our understanding of the origin of the Universe. This paper forecasts how well field-level inference of galaxy redshift surveys can constrain the amplitude of local primordial non-Gaussianity, f NLlocal, within a Bayesian hierarchical framework, in the upcoming Euclid data. We designed and simulated mock datasets and performed Markov chain Monte Carlo analyses using a full-field forward modelling approach. By including the formation history of the cosmic matter field in the analysis, the method takes into account all available probes of primordial non-Gaussianity, and goes beyond statistical summary estimators of f NLlocal. Probes include, for example, two-point and higher-order statistics, peculiar velocity fields, and scale-dependent galaxy biases. Furthermore, the method simultaneously handles systematic survey effects, such as selection effects, survey geometries, and galaxy biases. The forecast shows that, using simulated Euclid data, the method can achieve a precision of σ(f NLlocal) = 2.6 (68.3% confidence level), assuming a grid resolution of ΔL = 31.25 h −1 Mpc and a cut-off scale of k NF = 0.1 h Mpc−1. We also provide data products, including realistic simulations with non-zero values of f NLlocal and maps of adiabatic curvature fluctuations. The results underscore the feasibility and advantages of field-level inference to constrain f NLlocal in galaxy redshift surveys. Our approach consistently captures all the information available in the large-scale structure to constrain f NLlocal, and resolves the degeneracy between early-universe physics and late-time gravitational effects, while mitigating the impact of systematic and observational effects.


Publication metadata

Author(s): Andrews A, Jasche J, Lavaux G, Leclercq F, Finelli F, Akrami Y, Ballardini M, Karagiannis D, Valiviita J, Bartolo N, Canas-Herrera G, Casas S, Granett BR, Pace F, Paoletti D, Porqueres N, Sakr Z, Sapone D, Aghanim N, Amara A, Andreon S, Baccigalupi C, Baldi M, Bardelli S, Bonino D, Branchini E, Brescia M, Brinchmann J, Camera S, Capobianco V, Carbone C, Carretero J, Castellano M, Castignani G, Cavuoti S, Cimatti A, Colodro-Conde C, Congedo G, Conselice CJ, Conversi L, Copin Y, Courbin F, Courtois HM, Da Silva A, Degaudenzi H, De Lucia G, Di Giorgio AM, Dinis J, Dubath F, Duncan CAJ, Dupac X, Dusini S, Farina M, Farrens S, Faustini F, Ferriol S, Frailis M, Franceschi E, Galeotta S, Gillis B, Giocoli C, Gomez-Alvarez P, Grazian A, Grupp F, Haugan SVH, Holmes W, Hormuth F, Hornstrup A, Hudelot P, Ilic S, Jahnke K, Jhabvala M, Joachimi B, Keihanen E, Kermiche S, Kiessling A, Kubik B, Kunz M, Kurki-Suonio H, Ligori S, Lilje PB, Lindholm V, Lloro I, Maiorano E, Mansutti O, Marggraf O, Markovic K, Martinelli M, Martinet N, Marulli F, Massey R, Medinaceli E, Mei S, Mellier Y, Meneghetti M, Merlin E, Meylan G, Moresco M, Moscardini L, Neissner C, Niemi S-M, Nightingale JW, Padilla C, Paltani S, Pasian F, Pedersen K, Pettorino V, Pires S, Polenta G, Poncet M, Popa LA, Pozzetti L, Raison F, Rebolo R, Renzi A, Rhodes J, Riccio G, Romelli E, Roncarelli M, Saglia R, Sanchez AG, Sartoris B, Schirmer M, Schneider P, Schrabback T, Secroun A, Sefusatti E, Serrano S, Sirignano C, Sirri G, Stanco L, Steinwagner J, Tallada-Crespi P, Taylor AN, Tereno I, Toledo-Moreo R, Torradeflot F, Tutusaus I, Valenziano L, Vassallo T, Verdoes Kleijn G, Veropalumbo A, Wang Y, Weller J, Zamorani G, Zucca E, Burigana C, Scottez V, Spurio Mancini A, Viel M

Publication type: Article

Publication status: Published

Journal: Astronomy and Astrophysics

Year: 2026

Volume: 711

Online publication date: 03/07/2026

Acceptance date: 02/02/2026

Date deposited: 17/07/2026

ISSN (print): 0004-6361

ISSN (electronic): 1432-0746

Publisher: EDP Sciences

URL: https://doi.org/10.1051/0004-6361/202553802

DOI: 10.1051/0004-6361/202553802


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