Title: BlackTHUNDER – A non-stellar Balmer break in a black hole-dominated  little red dot at ȥ = 7.04
Authors: name: Xihan Ji
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Roberto Maiolino
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
name: Hannah Übler
affiliations: Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching
name: Jan Scholtz
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Francesco D’Eugenio
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Fengwu Sun
affiliations: Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
name: Michele Perna
affiliations: Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, Spain
name: Hannah Turner
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Santiago Arribas
affiliations: Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, Spain
name: Jake S. Bennett
affiliations: Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
name: Andrew Bunker
affiliations: University of Oxford, Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX13RH, UK
name: Stefano Carniani
affiliations: Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
name: Stéphane Charlot
affiliations: Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
name: Giovanni Cresci
affiliations: INAF - Osservatorio Astrofisico di Arcetri, largo E. Fermi 5, 50127 Firenze, Italy
name: Mirko Curti
affiliations: European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
name: Eiichi Egami
affiliations: Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721, USA
name: Andy Fabian
affiliations: Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
name: Kohei Inayoshi
affiliations: Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
name: Yuki Isobe
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
name: Gareth Jones
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Ignas Juodžbalis
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Nimisha Kumari
affiliations: AURA for European Space Agency, Space Telescope Science Institute, 3700 San Matin Drive, Baltimore, MD 21218, USA
name: Jianwei Lyu
affiliations: Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721, USA
name: Giovanni Mazzolari
affiliations: Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, I-40129 Bologna, Italy
INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, I-40129 Bologna, Italy
name: Eleonora Parlanti
affiliations: Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching
name: Brant Robertson
affiliations: Department of Astronomy and Astrophysics University of California, Santa Cruz, 1156 High Street, Santa Cruz CA 96054, USA
name: Bruno Rodríguez Del Pino
affiliations: Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, Spain
name: Raffaella Schneider
affiliations: Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
INAF/Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
INFN, Sezione Roma1, Dipartimento di Fisica, “Sapienza” Universita di Roma, Piazzale Aldo Moro 2, 00185, Roma, Italy
Sapienza School for Advanced Studies, Viale Regina Elena 291, 00161 Roma, Italy
name: Debora Sijacki
affiliations: Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
name: Sandro Tacchella
affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
name: Alessandro Trinca
affiliations: Como Lake Center for Astrophysics, DiSAT, Universita` degli Studi dell’Insubria, via Valleggio 11, 22100, Como, Italy
INAF/Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
Universite de Haute Alsace,F.S.T., 4, rue des Freres Lumiere -68093 MULHOUSE -France
name: Rosa Valiante
affiliations: INAF/Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
INFN, Sezione Roma1, Dipartimento di Fisica, “Sapienza” Universita di Roma, Piazzale Aldo Moro 2, 00185, Roma, Italy
name: Giacomo Venturi
affiliations: Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
name: Marta Volonteri
affiliations: Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
name: Chris Willott
affiliations: NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada
name: Callum Witten
affiliations: Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
name: Joris Witstok
affiliations: Cosmic Dawn Center (DAWN), Copenhagen, Denmark
Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200, Copenhagen, Denmark
Affiliations: Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching
Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
Centro de Astrobiología (CAB), CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, Spain
University of Oxford, Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX13RH, UK
Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
INAF - Osservatorio Astrofisico di Arcetri, largo E. Fermi 5, 50127 Firenze, Italy
European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
Steward Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721, USA
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
AURA for European Space Agency, Space Telescope Science Institute, 3700 San Matin Drive, Baltimore, MD 21218, USA
Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, I-40129 Bologna, Italy
INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, I-40129 Bologna, Italy
Department of Astronomy and Astrophysics University of California, Santa Cruz, 1156 High Street, Santa Cruz CA 96054, USA
Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
INAF/Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
INFN, Sezione Roma1, Dipartimento di Fisica, “Sapienza” Universita di Roma, Piazzale Aldo Moro 2, 00185, Roma, Italy
Sapienza School for Advanced Studies, Viale Regina Elena 291, 00161 Roma, Italy
Como Lake Center for Astrophysics, DiSAT, Universita` degli Studi dell’Insubria, via Valleggio 11, 22100, Como, Italy
Universite de Haute Alsace,F.S.T., 4, rue des Freres Lumiere -68093 MULHOUSE -France
NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada
Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
Cosmic Dawn Center (DAWN), Copenhagen, Denmark
Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200, Copenhagen, Denmark
Field: Physics and Astronomy
Document type: preprint
Year: 2025