The z = 9.625 Cosmic Gems galaxy was a compact “blue monster” propelled by massive star clusters

作者：E. Vanzella, Matteo Messa, Angela Adamo, F. Loiacono, Masamune Oguri, Keren Sharon, Larry Bradley, P. Bergamini, M. Meneghetti, Adélaïde Claeyssens, B. Welch, Maruša Bradač, A. Zanella, A. Bolamperti, F. Calura, Tiger Yu-Yang Hsiao, E. Zackrisson, Massimo Ricotti, L. Christensen, J. M. Diego, F. E. Bauer, Xinfeng Xu, S. Fujimoto, C. Grillo, M. Lombardi, P. Rosati, Tom Resseguier, Adi Zitrin, Arjan Bik, Johan Richard, Abdurrouf, Rachana Bhatawdekar, Dan Coe, Brenda Frye, Akio Inoue, Yolanda Jiménez-Teja, Colin Norman, Jane R. Rigby, M. Trenti, Takuya Hashimoto · 发表于：Astronomy and Astrophysics · 年份：2025 · DOI：10.1051/0004-6361/202556570 · 被引用次数：8 · 研究领域：Galaxies: Formation, Evolution, Phenomena、Stellar, planetary, and galactic studies、Astronomy and Astrophysical Research

The recent discovery of five massive stellar clusters at z = 9.625 in the Cosmic Gems galaxy has raised the question about the formation mechanism of star clusters in the first 500 Myr after the Big Bang. We inferred the total stellar mass in clusters by normalizing and integrating the stellar cluster mass function (SCMF, d n ( M )/d M = n 0 M β ), assuming three different slopes ( β = −1.5, −2.0, and −2.5) and different lower-mass limits between 10 2 and 10 5 M ⊙ . We compared the total integrated cluster stellar mass to the stellar mass inferred from the counter image of the Cosmic Gems, which provides the best modestly magnified ( μ = 1.84 ± 0.05) representation of the entire galaxy. The delensed stellar mass of the Cosmic Gems galaxy was estimated as 3.5 −1.8 +3.3 × 10 7 M ⊙ , with an effective radius of R eff = 103 −15 +13 parsecs and a stellar surface mass density of Σ mass = 520 −225 +340 M ⊙ pc −2 . Accounting for normalization uncertainties – including different lensing magnification scenarios for the arc – a modified SCMF, combined with a significantly high star cluster formation efficiency (approaching 100%), appears to be a necessary condition to explain the relatively short formation timescale of both the star clusters and the counter image, without exceeding the galaxy’s stellar mass. By extrapolating the physical properties at the peak of the burst, we found that in its recent past (≲30 Myr) the Cosmic Gems galaxy likely experienced a specific star formation ra...