Bound star clusters observed in a lensed galaxy 460 Myr after the Big Bang

Angela Adamo; Larry D Bradley; Eros Vanzella; Adélaïde Claeyssens; Brian Welch; Jose M Diego; Guillaume Mahler; Masamune Oguri; Keren Sharon; Abdurro'uf; Tiger Yu-Yang Hsiao; Xinfeng Xu; Matteo Messa; Augusto E Lassen; Erik Zackrisson; Gabriel Brammer; Dan Coe; Vasily Kokorev; Massimo Ricotti; Adi Zitrin; Seiji Fujimoto; Akio K Inoue; Tom Resseguier; Jane R Rigby; Yolanda Jiménez-Teja; Rogier A Windhorst; Takuya Hashimoto; Yoichi Tamura

doi:10.1038/s41586-024-07703-7

Bound star clusters observed in a lensed galaxy 460 Myr after the Big Bang

Nature. 2024 Aug;632(8025):513-516. doi: 10.1038/s41586-024-07703-7. Epub 2024 Jun 24.

Authors

Angela Adamo¹, Larry D Bradley^#², Eros Vanzella^#³, Adélaïde Claeyssens⁴, Brian Welch^{5

6}, Jose M Diego⁷, Guillaume Mahler^{8

9

10}, Masamune Oguri^{11

12}, Keren Sharon¹³, Abdurro'uf^{2

14}, Tiger Yu-Yang Hsiao^{2

14}, Xinfeng Xu^{15

16}, Matteo Messa³, Augusto E Lassen^{4

17}, Erik Zackrisson^{18

19}, Gabriel Brammer^{20

21}, Dan Coe^{2

14

22}, Vasily Kokorev²³, Massimo Ricotti⁵, Adi Zitrin²⁴, Seiji Fujimoto²⁵, Akio K Inoue^{26

27}, Tom Resseguier¹⁴, Jane R Rigby⁶, Yolanda Jiménez-Teja^{28

29}, Rogier A Windhorst³⁰, Takuya Hashimoto^{31

32}, Yoichi Tamura³³

Affiliations

¹ Astronomy Department, Stockholm University and Oskar Klein Centre, Stockholm, Sweden. [email protected].
² Space Telescope Science Institute (STScI), Baltimore, MD, USA.
³ Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, INAF, Bologna, Italy.
⁴ Astronomy Department, Stockholm University and Oskar Klein Centre, Stockholm, Sweden.
⁵ Department of Astronomy, University of Maryland, College Park, MD, USA.
⁶ Astrophysics Science Division, Code 660, NASA Goddard Space Flight Center, Greenbelt, MD, USA.
⁷ Instituto de Física de Cantabria, CSIC-UC, Santander, Spain.
⁸ STAR Institute, Liège, Belgium.
⁹ Centre for Extragalactic Astronomy, Durham University, Durham, UK.
¹⁰ Institute for Computational Cosmology, Durham University, Durham, UK.
¹¹ Center for Frontier Science, Chiba University, Chiba, Japan.
¹² Department of Physics, Graduate School of Science, Chiba University, Chiba, Japan.
¹³ Department of Astronomy, University of Michigan, Ann Arbor, MI, USA.
¹⁴ Center for Astrophysical Sciences, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, USA.
¹⁵ Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA.
¹⁶ Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University, Evanston, IL, USA.
¹⁷ Instituto de Física, Departamento de Astronomia, Universe Federal do Rio Grande do Sul, Porto Alegre, Brazil.
¹⁸ Observational Astrophysics, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
¹⁹ Swedish Collegium for Advanced Study, Uppsala, Sweden.
²⁰ Cosmic Dawn Center (DAWN), Copenhagen, Denmark.
²¹ Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
²² Association of Universities for Research in Astronomy (AURA) for the European Space Agency (ESA), STScI, Baltimore, MD, USA.
²³ Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands.
²⁴ Department of Physics, Ben-Gurion University of the Negev, Be'er-Sheva, Israel.
²⁵ Department of Astronomy, The University of Texas at Austin, Austin, TX, USA.
²⁶ Department of Physics, School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁷ Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
²⁸ Instituto de Astrofísica de Andalucía, (CSIC), Granada, Spain.
²⁹ Observatório Nacional, (MCTI), Rio de Janeiro, Brazil.
³⁰ School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA.
³¹ Division of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan.
³² Tomonaga Center for the History of the Universe (TCHoU), University of Tsukuba, Tsukuba, Japan.
³³ Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan.

^# Contributed equally.

Abstract

The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. ¹). However, it is an intrinsically ultraviolet faint galaxy, in the range of those now thought to drive the reionization of the Universe^2-4. Hitherto the smallest features resolved in a galaxy at a comparable redshift are between a few hundreds and a few tens of parsecs (pc)^5,6. Here we report JWST observations of the Cosmic Gems. The light of the galaxy is resolved into five star clusters located in a region smaller than 70 pc. They exhibit minimal dust attenuation and low metallicity, ages younger than 50 Myr and intrinsic masses of about 10⁶M_⊙. Their lensing-corrected sizes are approximately 1 pc, resulting in stellar surface densities near 10⁵M_⊙ pc^-2, three orders of magnitude higher than typical young star clusters in the local Universe⁷. Despite the uncertainties inherent to the lensing model, they are consistent with being gravitationally bound stellar systems, that is, proto-globular clusters. We conclude that star cluster formation and feedback likely contributed to shaping the properties of galaxies during the epoch of reionization.