A first GLIMPSE into star-cluster populations across cosmic time
9 affiliations
- 1Univ Lyon, Univ Lyon1, Ens de Lyon, CNRS, CRAL UMR5574
- 2Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Center
- 3Cosmic Frontier Center, The University of Texas at Austin
- 4Department of Astronomy, The University of Texas at Austin
- 5Centre for Extragalactic Astronomy, Department of Physics, Durham University
- 6Institute for Computational Cosmology, Department of Physics, Durham University
- 7Department of Astronomy, University of Geneva
- 8Institut d’Astrophysique de Paris, CNRS, Sorbonne Université
- 9Department of Physics & Astronomy, Tufts University
Abstract
We present the first sample of 218 high-redshift ( z > 0.5) star clusters, detected with JWST/NIRCam in 78 magnified galaxies from different galaxy cluster fields. The majority of the systems (~60%) are observed in the very deep NIRCam observations of the cluster AbellS1063 (GLIMPSE program), showing the power that deep observations, combined with lensing, has to reveal these primordial stellar structures. We performed simultaneous size–flux estimates in all available NIRCam filters and spectral energy distribution (SED) fitting analysis to recover star-cluster physical properties. All star-cluster candidates have very high magnification (µ>10). Star clusters and clumps show similar ages and redshift distributions, although noticeable differences are seen in their masses, sizes and stellar surface densities inherent to the lack of resolution in the latter group. We reconstructed the formation redshift of star clusters and find that the vast majority of the observed star clusters show young ages (<100 Myr) and seem to have formed at cosmic noon (CN; 1 < z < 4). A small sample of CN star clusters are about 1 Gyr old; these potential globular clusters formed well within cosmic reionization. Star clusters have stellar densities in the range of 10 2 to 10 6 M ⊙ /pc 2 , with median values around 10 4 M ⊙ /pc 2 . Their sizes and densities better overlap with those of nuclear star clusters in the local Universe. These intrinsic properties make high-z star clusters a viable channel to grow intermediate-mass black holes. We used Bayesian inference to make the first direct measurement of the starcluster mass function at z > 1 based on a subsample of 60 star clusters younger than 100 Myr and with masses above 2 × 10 6 M ⊙ . The star cluster mass function is well described by a power law with a slope of β 50% = −1.89 −0.12 +0.13 , suggesting that a power-law -2 function might already be in place in the distant Universe.
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BibTeX
@article{claeyssens2026first,
title = {{A first GLIMPSE into star-cluster populations across cosmic time}},
author = {Adélaïde Claeyssens and A. Adamo and Vasily Kokorev and Lukas J. Furtak and Johan Richard and Benjamin Beauchesne and Miroslava Dessauges-Zavadsky and Hakim Atek and J. Chisholm and Ryan Endsley and S. Fujimoto and Damien Korber and R. Pan and Alberto Saldana-Lopez and D. Schaerer},
journal = {Astronomy \& Astrophysics - A\&A},
year = {2026},
month = aug,
doi = {10.1051/0004-6361/202659135},
url = {https://hal.science/hal-05847980v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A first GLIMPSE into star-cluster populations across cosmic time
AU - Adélaïde Claeyssens
AU - A. Adamo
AU - Vasily Kokorev
AU - Lukas J. Furtak
AU - Johan Richard
AU - Benjamin Beauchesne
AU - Miroslava Dessauges-Zavadsky
AU - Hakim Atek
AU - J. Chisholm
AU - Ryan Endsley
AU - S. Fujimoto
AU - Damien Korber
AU - R. Pan
AU - Alberto Saldana-Lopez
AU - D. Schaerer
PY - 2026
DA - 2026/08/20
JO - Astronomy & Astrophysics - A&A
DO - 10.1051/0004-6361/202659135
UR - https://hal.science/hal-05847980v1
AB - We present the first sample of 218 high-redshift ( z > 0.5) star clusters, detected with JWST/NIRCam in 78 magnified galaxies from different galaxy cluster fields. The majority of the systems (~60%) are observed in the very deep NIRCam observations of the cluster AbellS1063 (GLIMPSE program), showing the power that deep observations, combined with lensing, has to reveal these primordial stellar structures. We performed simultaneous size–flux estimates in all available NIRCam filters and spectral energy distribution (SED) fitting analysis to recover star-cluster physical properties. All star-cluster candidates have very high magnification (µ>10). Star clusters and clumps show similar ages and redshift distributions, although noticeable differences are seen in their masses, sizes and stellar surface densities inherent to the lack of resolution in the latter group. We reconstructed the formation redshift of star clusters and find that the vast majority of the observed star clusters show young ages (<100 Myr) and seem to have formed at cosmic noon (CN; 1 < z < 4). A small sample of CN star clusters are about 1 Gyr old; these potential globular clusters formed well within cosmic reionization. Star clusters have stellar densities in the range of 10 2 to 10 6 M ⊙ /pc 2 , with median values around 10 4 M ⊙ /pc 2 . Their sizes and densities better overlap with those of nuclear star clusters in the local Universe. These intrinsic properties make high-z star clusters a viable channel to grow intermediate-mass black holes. We used Bayesian inference to make the first direct measurement of the starcluster mass function at z > 1 based on a subsample of 60 star clusters younger than 100 Myr and with masses above 2 × 10 6 M ⊙ . The star cluster mass function is well described by a power law with a slope of β 50% = −1.89 −0.12 +0.13 , suggesting that a power-law -2 function might already be in place in the distant Universe.
SN - 0004-6361
SN - 1432-0746
ER -