A first GLIMPSE into star clusters populations across cosmic time

Adélaïde Claeyssens; Angela Adamo; Vasily Kokorev; Lukas Furtak; Johan Richard; Benjamin Beauchesne; Miroslava Dessauges-Zavadsky; Hakim Atek; John Chisholm; Ryan Endsley; Seiji Fujimoto; Damien Korber; Richard Pan; Alberto Saldana-Lopez; Daniel Schaerer

arXiv · 2601.16281

A first GLIMPSE into star clusters populations across cosmic time

Adélaïde Claeyssens·Angela Adamo·Vasily Kokorev·Lukas Furtak·Johan Richard·Benjamin Beauchesne·Miroslava Dessauges-Zavadsky·Hakim Atek·John Chisholm·Ryan Endsley·Seiji Fujimoto·Damien Korber·Richard Pan·Alberto Saldana-Lopez·Daniel Schaerer

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Abstract

We present the first sample of 222 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%) is 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 perform 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. 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 reconstruct the formation redshift of star clusters and find that the large majority of the observed star clusters show young ages (<100 Myr) and seems to form at cosmic noon (CN,1 1, based on a subsample of 60 star clusters younger than 100 Myr and with masses above 2e6 Msun. The star cluster mass function is well described by a power-law with slope beta = -1.89 suggesting that a power-law -2 function might already be in place in the distant Universe.

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Adélaïde Claeyssens, Angela Adamo, Vasily Kokorev, Lukas Furtak, Johan Richard, Benjamin Beauchesne, Miroslava Dessauges-Zavadsky, Hakim Atek, John Chisholm, Ryan Endsley, Seiji Fujimoto, Damien Korber, Richard Pan, Alberto Saldana-Lopez, Daniel Schaerer. 2026-01-22. A first GLIMPSE into star clusters populations across cosmic time. https://arxiv.org/abs/2601.16281

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