Euclid: Testing the Copernican principle with next-generation surveys^⋆

¹ PPGCosmo, Universidade Federal do Espírito Santo, 29075-910 Vitória, ES, Brazil
e-mail: dacato115@gmail.com
² Núcleo Cosmo-ufes & Departamento de Física, Universidade Federal do Espírito Santo, 29075-910 Vitória, ES, Brazil
³ INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
⁴ IFPU, Institute for Fundamental Physics of the Universe, Via Beirut 2, 34151 Trieste, Italy
⁵ Institut de Recherche en Astrophysique et Planétologie (IRAP), Université de Toulouse, CNRS, UPS, CNES, 14 Av. Édouard Belin, 31400 Toulouse, France
⁶ Institut für Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany
⁷ Université St. Joseph; Faculty of Sciences, Beirut, Lebanon
⁸ Instituto de Física Teórica UAM-CSIC, Campus de Cantoblanco, 28049 Madrid, Spain
⁹ Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo Grande, 1749-016 Lisboa, Portugal
¹⁰ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
¹¹ Institut de Physique Théorique, CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹² Université de Genève, Département de Physique Théorique and Centre for Astroparticle Physics, 24 Quai Ernest-Ansermet, 1211 Genève 4, Switzerland
¹³ INAF-Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Italy
¹⁴ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁵ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
¹⁶ Departamento de Física, FCFM, Universidad de Chile, Blanco Encalada 2008, Santiago, Chile
¹⁷ School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK
¹⁸ Dipartimento di Fisica, Universitá degli Studi di Torino, Via P. Giuria 1, 10125 Torino, Italy
¹⁹ INFN-Sezione di Torino, Via P. Giuria 1, 10125 Torino, Italy
²⁰ INAF-Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, TO, Italy
²¹ INAF-IASF Milano, Via Alfonso Corti 12, 20133 Milano, Italy
²² Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University, 52056 Aachen, Germany
²³ Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
²⁴ Centre National d’Études Spatiales, Toulouse, France
²⁵ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, Astrophysique, Instrumentation et Modélisation Paris-Saclay, 91191 Gif-sur-Yvette, France
²⁶ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
²⁷ Institut d’Estudis Espacials de Catalunya (IEEC), Carrer Gran Capitá 2-4, 08034 Barcelona, Spain
²⁸ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
²⁹ ESAC/ESA, Camino Bajo del Castillo, s/n., Urb. Villafranca del Castillo, 28692 Villanueva de la Cañada, Madrid, Spain
³⁰ Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK
³¹ INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
³² Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Università di Bologna, Via Piero Gobetti 93/2, 40129 Bologna, Italy
³³ INFN-Sezione di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
³⁴ Dipartimento di Fisica, Universitá degli Studi di Genova, and INFN-Sezione di Genova, Via Dodecaneso 33, 16146 Genova, Italy
³⁵ INFN-Sezione di Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
³⁶ INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
³⁷ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
³⁸ Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Barcelona, Spain
³⁹ Port d’Informació Científica, Campus UAB, C. Albareda s/n, 08193 Bellaterra, Barcelona, Spain
⁴⁰ INFN Section of Naples, Via Cinthia 6, 80126 Napoli, Italy
⁴¹ Department of Physics “E. Pancini”, University Federico II, Via Cinthia 6, 80126 Napoli, Italy
⁴² Dipartimento di Fisica e Astronomia “Augusto Righi” – Alma Mater Studiorum Universitá di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
⁴³ INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁴⁴ Institut National de Physique Nucléaire et de Physique des Particules, 3 Rue Michel-Ange, 75794 Paris Cédex 16, France
⁴⁵ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁴⁶ European Space Agency/ESRIN, Largo Galileo Galilei 1, 00044 Frascati, Roma, Italy
⁴⁷ Univ. Lyon, Univ. Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, 69622 Villeurbanne, France
⁴⁸ Observatoire de Sauverny, École Polytechnique Fédérale de Lausanne, 1290 Versoix, Switzerland
⁴⁹ Department of Astronomy, University of Geneva, Ch. dÉcogia 16, 1290 Versoix, Switzerland
⁵⁰ Department of Physics, Oxford University, Keble Road, Oxford OX1 3RH, UK
⁵¹ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁵² INFN-Padova, Via Marzolo 8, 35131 Padova, Italy
⁵³ Istituto Nazionale di Astrofisica (INAF) – Osservatorio di Astrofisica e Scienza dello Spazio (OAS), Via Gobetti 93/3, 40127 Bologna, Italy
⁵⁴ Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁵⁵ INAF-Osservatorio Astronomico di Padova, Via dell’Osservatorio 5, 35122 Padova, Italy
⁵⁶ Max Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, 85748 Garching, Germany
⁵⁷ Universitäts-Sternwarte München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstrasse 1, 81679 München, Germany
⁵⁸ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern 0315 Oslo, Norway
⁵⁹ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁶⁰ von Hoerner & Sulger GmbH, SchloßPlatz 8, 68723 Schwetzingen, Germany
⁶¹ Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
⁶² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁶³ Department of Physics and Helsinki Institute of Physics, University of Helsinki, Gustaf Hällströmin katu 2, 00014 Helsinki, Finland
⁶⁴ NOVA Optical Infrared Instrumentation Group at ASTRON, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
⁶⁵ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁶⁶ Department of Physics, Institute for Computational Cosmology, Durham University, South Road DH1 3LE, UK
⁶⁷ INFN-Bologna, Via Irnerio 46, 40126 Bologna, Italy
⁶⁸ Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
⁶⁹ European Space Agency/ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
⁷⁰ Department of Physics and Astronomy, University of Aarhus, Ny Munkegade 120, 8000 Aarhus C, Denmark
⁷¹ Space Science Data Center, Italian Space Agency, Via del Politecnico snc, 00133 Roma, Italy
⁷² Institute of Space Science, Bucharest 077125, Romania
⁷³ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38204 San Cristóbal de La Laguna, Tenerife, Spain
⁷⁴ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
⁷⁵ Aix-Marseille Univ., CNRS/IN2P3, CPPM, Marseille, France
⁷⁶ Dipartimento di Fisica e Astronomia “G. Galilei”, Universitá di Padova, Via Marzolo 8, 35131 Padova, Italy
⁷⁷ Aix-Marseille Univ., CNRS, CNES, LAM, Marseille, France
⁷⁸ Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avenida Complutense 40, 28040 Madrid, Spain
⁷⁹ Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
⁸⁰ Universidad Politécnica de Cartagena, Departamento de Electrónica y Tecnología de Computadoras, 30202 Cartagena, Spain
⁸¹ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
⁸² Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
⁸³ INAF-Osservatorio Astronomico di Brera, Via Brera 28, 20122 Milano, Italy
⁸⁴ Institut d’Astrophysique de Paris, UMR 7095, CNRS, et Sorbonne Université, 98 bis Boulevard Arago, 75014 Paris, France
⁸⁵ Junia, EPA Department, 59000 Lille, France

Received: 20 July 2022
Accepted: 29 September 2022

Abstract

Context. The Copernican principle, the notion that we are not at a special location in the Universe, is one of the cornerstones of modern cosmology. Its violation would invalidate the Friedmann-Lemaître-Robertson-Walker metric, causing a major change in our understanding of the Universe. Thus, it is of fundamental importance to perform observational tests of this principle.

Aims. We determine the precision with which future surveys will be able to test the Copernican principle and their ability to detect any possible violations.

Methods. We forecast constraints on the inhomogeneous Lemaître-Tolman-Bondi (LTB) model with a cosmological constant Λ, basically a cosmological constant Λ and cold dark matter (CDM) model but endowed with a spherical inhomogeneity. We consider combinations of currently available data and simulated Euclid data, together with external data products, based on both ΛCDM and ΛLTB fiducial models. These constraints are compared to the expectations from the Copernican principle.

Results. When considering the ΛCDM fiducial model, we find that Euclid data, in combination with other current and forthcoming surveys, will improve the constraints on the Copernican principle by about 30%, with ±10% variations depending on the observables and scales considered. On the other hand, when considering a ΛLTB fiducial model, we find that future Euclid data, combined with other current and forthcoming datasets, will be able to detect gigaparsec-scale inhomogeneities of contrast −0.1.

Conclusions. Next-generation surveys, such as Euclid, will thoroughly test homogeneity at large scales, tightening the constraints on possible violations of the Copernican principle.