The Science of the Einstein Telescope

Journal of Cosmology and Astroparticle Physics, vol. 2026, pp. 081

Abstract

Abstract Einstein Telescope (ET) is the European project for a gravitational-wave (GW) observatory of third-generation. In this paper we present a comprehensive discussion of its science objectives, providing state-of-the-art predictions for the capabilities of ET in both geometries currently under consideration, a single-site triangular configuration or two L-shaped detectors. We discuss the impact that ET will have on domains as broad and diverse as fundamental physics, cosmology, early Universe, astrophysics of compact objects, physics of matter in extreme conditions, and dynamics of stellar collapse. We discuss how the study of extreme astrophysical events will be enhanced by multi-messenger observations. We highlight the ET synergies with ground-based and space-borne GW observatories, including multi-band investigations of the same sources, improved parameter estimation, and complementary information on astrophysical or cosmological mechanisms obtained combining observations from different frequency bands. We present advancements in waveform modeling dedicated to third-generation observatories, along with open tools developed within the ET Collaboration for assessing the scientific potentials of different detector configurations. We finally discuss the data analysis challenges posed by third-generation observatories, which will enable access to large populations of sources and provide unprecedented precision.

Authors 60

1. Adrian Abac

   Max Planck Institute for Gravitational Physics

   Affiliation as printed

   Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam, Germany

2. L. Raul Abramo

   Universidade de São Paulo

   Affiliation as printed

   Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, 05508-090, São Paulo, SP, Brazil

3. Simone Albanesi

   Istituto Nazionale di Fisica Nucleare, Sezione di Torino · Friedrich Schiller University Jena

   Affiliation as printed

   INFN sezione di Torino, Torino, 10125, Italy

   Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany

4. Angelica Albertini

   Charles University · Czech Academy of Sciences, Astronomical Institute

   Affiliation as printed

   Astronomical Institute of the Czech Academy of Sciences, Boční II 1401/1a, CZ-141 00 Prague, Czech Republic

   Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague, Czech Republic

5. A. Agapito

   Centre National de la Recherche Scientifique · Université de Toulon · Aix-Marseille Université · Istituto Nazionale di Fisica Nucleare, Sezione di Roma I · Sapienza University of Rome

   Affiliation as printed

   Aix-Marseille Université, Université de Toulon, CNRS, CPT, Marseille, France

   Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Roma, Italy

   INFN - Sezione di Roma, Piazzale Aldo Moro 2, 00185, Roma, Italy

6. M. Agathos

   Queen Mary University of London · University of Cambridge

   Affiliation as printed

   DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom

   School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom

7. C. Albertus

   Universidad de Salamanca

   Affiliation as printed

   Department of Fundamental Physics and IUFFyM, University of Salamanca, Plaza de la Merced S/N E-37008, Salamanca, Spain

8. Nils Andersson

   University of Southampton

   Affiliation as printed

   Mathematical Sciences and STAG Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom

9. Tomás Andrade

   Institut de Ciències del Cosmos · Universitat de Barcelona

   Affiliation as printed

   Institut de Ciències del Cosmos Universitat de Barcelona (ICCUB), c. Martí i Franquès, 1, 08028 Barcelona, Spain

10. Igor Andreoni

    University of North Carolina at Chapel Hill · Joint Space Science Institute · University of Maryland, College Park

    Affiliation as printed

    Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, U.S.A

    Joint Space-Science Institute, University of Maryland, College Park, MD 20742, U.S.A

11. Federico Angeloni

    University of Rome Tor Vergata · Astronomical Observatory of Rome · Istituto Nazionale di Fisica Nucleare, Sezione di Roma I · Sapienza University of Rome · National Institute for Astrophysics

    Affiliation as printed

    Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185, Roma, Italy

    Dipartimento di Fisica, Università degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133, Roma, Italy

    INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00078 Monte Porzio Catone (RM), Italy

    INFN - Sezione di Roma, Piazzale Aldo Moro 2, 00185, Roma, Italy

12. Marco Antonelli

    Centre National de la Recherche Scientifique · Laboratoire de Physique Corpusculaire de Caen · Institut National de Physique Nucléaire et de Physique des Particules

    Affiliation as printed

    Laboratoire de Physique Corpusculaire (LPC-Caen), CNRS/IN2P3, 6 Bvd du maréchal Juin, 14050 Caen, France

13. John Antoniadis

    Max Planck Institute for Radio Astronomy · Foundation for Research and Technology Hellas

    Affiliation as printed

    Institute of Astrophysics, Foundation for Research and Technology - Hellas, N. Plastira 100, 70013, Heraklion, Greece

    Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121, Bonn, Germany

14. Fabio Antonini

    Cardiff University

    Affiliation as printed

    Gravity Exploration Institute, School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, United Kingdom

15. Manuel Arca Sedda

    University of Padua · Istituto Nazionale di Fisica Nucleare · Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso · Collurania Teramo Observatory · Gran Sasso Science Institute · National Institute for Astrophysics

    Affiliation as printed

    Gran Sasso Science Institute, L'Aquila (AQ), I-67100, Italy

    INAF - Osservatorio Astronomico d’Abruzzo, Teramo, Italy

    INFN - Laboratori Nazionali del Gran Sasso, Assergi, I-67100, Italy

    Physics and Astronomy Department “Galileo Galilei”, University of Padova, Via Marzolo 8, 35131 Padova, Italy

16. M. Celeste Artale

    Universidad Andrés Bello · Heidelberg University

    Affiliation as printed

    Institut für Theoretische Astrophysik, Zentrum für Astronomie Heidelberg (ZAH), Universität Heidelberg, Albert-Ueberle-Straße 2, 69120, Heidelberg, Germany

    Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Fisica, Instituto de Astrofisica, Fernandez Concha 700, Las Condes, Santiago RM, Chile

17. S. Ascenzi

    Gran Sasso Science Institute

    Affiliation as printed

    Gran Sasso Science Institute, L'Aquila (AQ), I-67100, Italy

18. Pierre Auclair

    UCLouvain

    Affiliation as printed

    Cosmology, Universe and Relativity at Louvain (CURL), Institute of Mathematics and Physics, University of Louvain, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve, Belgium

19. Matteo Bachetti

    Osservatorio Astronomico di Cagliari

    Affiliation as printed

    INAF - Osservatorio Astronomico di Cagliari, via della Scienza 5, 09047 Selargius (CA), Italy

20. C. Badger

    King's College London

    Affiliation as printed

    King's College London, Physics Department, Strand, London WC2R 2LS, United Kingdom

21. B. Banerjee

    Gran Sasso Science Institute

    Affiliation as printed

    Gran Sasso Science Institute, L'Aquila (AQ), I-67100, Italy

22. D. Barba-González

    Universidad de Salamanca

    Affiliation as printed

    Department of Fundamental Physics and IUFFyM, University of Salamanca, Plaza de la Merced S/N E-37008, Salamanca, Spain

23. D. Barta

    HUN-REN Wigner Research Centre for Physics

    Affiliation as printed

    HUN-REN Wigner Research Centre for Physics, Konkoly-Thege Miklós út 29-33, 1121 Budapest, Hungary

24. N. Bartolo

    University of Padua · Istituto Nazionale di Fisica Nucleare, Sezione di Padova · Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF - Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio, 5, I-35122 Padova (PD), Italy

    INFN - Padova, Via Marzolo 8, 35131 Padova, Italy

    Physics and Astronomy Department “Galileo Galilei”, University of Padova, Via Marzolo 8, 35131 Padova, Italy

25. Andreas Bauswein

    GSI Helmholtz Centre for Heavy Ion Research

    Affiliation as printed

    GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany

26. Andrea Begnoni

    University of Padua · Istituto Nazionale di Fisica Nucleare, Sezione di Padova

    Affiliation as printed

    INFN - Padova, Via Marzolo 8, 35131 Padova, Italy

    Physics and Astronomy Department “Galileo Galilei”, University of Padova, Via Marzolo 8, 35131 Padova, Italy

27. F. Beirnaert

    Ghent University

    Affiliation as printed

    Universiteit Gent, B-9000 Gent, Belgium

28. M. Bejger

    Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara · Nicolaus Copernicus Astronomical Center

    Affiliation as printed

    INFN Sezione di Ferrara, Via Saragat 1, 44122 Ferrara, Italy

    Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warszawa, Poland

29. Enis Belgacem

    University of Geneva

    Affiliation as printed

    Département de Physique Théorique, Université de Genève, 24 quai Ernest Ansermet, 1211 Genève 4, Switzerland

    Gravitational Wave Science Center (GWSC), Université de Genève, CH-1211 Geneva, Switzerland

30. Nicola Bellomo

    University of Padua · Istituto Nazionale di Fisica Nucleare, Sezione di Padova · Osservatorio Astronomico di Padova · National Institute for Astrophysics

    Affiliation as printed

    INAF - Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio, 5, I-35122 Padova (PD), Italy

    INFN - Padova, Via Marzolo 8, 35131 Padova, Italy

    Physics and Astronomy Department “Galileo Galilei”, University of Padova, Via Marzolo 8, 35131 Padova, Italy

31. Laura Bernard

    Centre National de la Recherche Scientifique · Université Paris Cité · Université Paris Sciences et Lettres · Observatoire de Paris · Laboratoire Univers et Théories

    Affiliation as printed

    Laboratoire Univers et Théories, Observatoire de Paris, Université PSL, Université Paris Cité, CNRS, F-92190 Meudon, France

32. Maria Grazia Bernardini

    Brera Astronomical Observatory

    Affiliation as printed

    INAF - Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate, Italy

33. Sebastiano Bernuzzi

    Friedrich Schiller University Jena

    Affiliation as printed

    Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany

34. C. P. L. Berry

    University of Glasgow

    Affiliation as printed

    Institute for Gravitational Research, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom

35. Emanuele Berti

    Johns Hopkins University

    Affiliation as printed

    William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, U.S.A

36. Gianfranco Bertone

    Institute of Physics · University of Amsterdam

    Affiliation as printed

    GRAPPA, Anton-Pannekoek Institute for Astronomy, Institute of Physics, Universiteit van Amsterdam, Amsterdam, The Netherlands

37. Dario Bettoni

    Universidad de Salamanca · Universidad de León

    Affiliation as printed

    Department of Fundamental Physics and IUFFyM, University of Salamanca, Plaza de la Merced S/N E-37008, Salamanca, Spain

    Department of Mathematics, University of León, Campus de Vegazana, s/n 24071 León, Spain

38. Miguel Bezares

    University of Nottingham

    Affiliation as printed

    Nottingham Centre of Gravity, Nottingham NG7 2RD, United Kingdom

    School of Mathematical Sciences & School of Physics and Astronomy, University of Nottingham, University Park, NG7 2RD, Nottingham, U.K

39. Swetha Bhagwat

    University of Birmingham

    Affiliation as printed

    School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom

40. S Bisero

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris

    Affiliation as printed

    Observatoire de Paris, CNRS, Université PSL, 5 place Jules Janssen, 92915 Meudon, France

41. M. A. Bizouard

    Centre National de la Recherche Scientifique · Université Côte d'Azur · Astrophysique Relativiste, Théories, Expériences, Métrologie, Instrumentation, Signaux · Observatoire de la Côte d’Azur

    Affiliation as printed

    Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Artemis, F-06304 Nice, France

42. Jose Juan Blanco-Pillado

    Ikerbasque · University of the Basque Country

    Affiliation as printed

    Department of Physics, University of the Basque Country UPV/EHU, 48080, Bilbao, Spain

    EHU Quantum Center, University of the Basque Country UPV/EHU, Bilbao, Spain

    IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain

43. Simone Blasi

    Vrije Universiteit Brussel · Deutsches Elektronen-Synchrotron DESY

    Affiliation as printed

    Department of Physics & Astronomy, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium

    Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany

44. A. Bonino

    University of Birmingham

    Affiliation as printed

    School of Physics and Astronomy and Institute for Gravitational Wave Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom

45. A. Borghese

    Astronomical Observatory of Rome · National Institute for Astrophysics

    Affiliation as printed

    INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00078 Monte Porzio Catone (RM), Italy

46. T. Bulik

    University of Warsaw

    Affiliation as printed

    Astronomical Observatory, University of Warsaw, al. Ujazdowskie 4, 00-478 Warsaw, Poland

47. Alessandra Buonanno

    Max Planck Institute for Gravitational Physics · University of Maryland, College Park

    Affiliation as printed

    Department of Physics, University of Maryland, College Park, MD 20742, U.S.A

    Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam, Germany

48. G. F. Burgio

    Istituto Nazionale di Fisica Nucleare, Sezione di Catania

    Affiliation as printed

    INFN Sezione di Catania, Via S. Sofia 64, 95123 Catania, Italy

49. S. Canevarolo

    Utrecht University

    Affiliation as printed

    Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands

50. C. Carbone

    Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano

    Affiliation as printed

    INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica, Via Alfonso Corti 12, I-20133, Milano, Italy

51. Pablo Cerdá-Durán

    Universitat de València

    Affiliation as printed

    Departament d'Astronomia i Astrofísica, Universitat de València, E-46100 Burjassot, València, Spain

    Observatori Astronòmic, Universitat de València, E-46980 Paterna, València, Spain

52. S. Chaty

    Centre National de la Recherche Scientifique · Université Paris Cité

    Affiliation as printed

    Université Paris Cité, CNRS, Astroparticule et Cosmologie, F-75013 Paris, France

53. T. Chiarusi

    Istituto Nazionale di Fisica Nucleare, Sezione di Bologna

    Affiliation as printed

    INFN - Bologna, Viale C. Berti Pichat 6/2, 40127 Bologna, Italy

54. Philippa S. Cole

    Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca · University of Milano-Bicocca

    Affiliation as printed

    Dipartimento di Fisica G. Occhialini, Università di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, Italy

    INFN - Sezione di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, Italy

55. Giulia Cusin

    University of Geneva · Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université

    Affiliation as printed

    Département de Physique Théorique, Université de Genève, 24 quai Ernest Ansermet, 1211 Genève 4, Switzerland

    Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris (IAP), 98 bis boulevard Arago, 75014 Paris, France

56. T. Dal Canton

    Centre National de la Recherche Scientifique · Université Paris-Saclay · Institut National de Physique Nucléaire et de Physique des Particules · Laboratoire de Physique des 2 Infinis Irène Joliot-Curie

    Affiliation as printed

    Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France

57. G. Dálya

    Centre National de la Recherche Scientifique · Université Toulouse III - Paul Sabatier · Institut National de Physique Nucléaire et de Physique des Particules · Laboratoire des 2 Infinis Toulouse · Université de Toulouse

    Affiliation as printed

    Laboratoire des 2 Infinis - Toulouse (L2IT-IN2P3), Université de Toulouse, CNRS, UPS, F-31062 Toulouse Cedex 9, France

58. W. Del Pozzo

    University of Pisa · Istituto Nazionale di Fisica Nucleare, Sezione di Pisa

    Affiliation as printed

    Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy

    INFN - Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy

59. Alessio Ludovico de Santis

    University of Pisa · Istituto Nazionale di Fisica Nucleare, Sezione di Pisa

    Affiliation as printed

    Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy

    INFN - Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy

60. Irina Dvorkin

    Centre National de la Recherche Scientifique · Institut Universitaire de France · Institut d'Astrophysique de Paris · Sorbonne Université · Ministère de l'Enseignement Supérieur, de la Recherche et de l'Espace

    Affiliation as printed

    Institut Universitaire de France, Ministére de l’Enseignement Supérieur et de la Recherche, 1 rue Descartes, 75231 Paris Cedex F-05, France

    Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris (IAP), 98 bis boulevard Arago, 75014 Paris, France