Massive Star Formation at Supersolar Metallicities: Constraints on the Initial Mass Function

作者：Eda Gjergo, Zhi-Yu Zhang, Pavel Kroupa, Aleksei Sorokin, Zhiqiang Yan, Ziyi Guo, Tereza Jerabkova, Akram Hasani Zonoozi, Hosein Haghi · 发表于：Research in Astronomy and Astrophysics · 年份：2025 · DOI：10.1088/1674-4527/ae1f79 · 被引用次数：7 · 研究领域：Astrophysics and Star Formation Studies、Stellar, planetary, and galactic studies、Fullerene Chemistry and Applications

Abstract Metals enhance the cooling efficiency of molecular clouds, promoting fragmentation. Consequently, increasing the metallicity may boost the formation of low-mass stars. Within the integrated galactic initial mass function (IGIMF) theory, this effect is empirically captured by a linear relation between the slope of the low-mass stellar IMF, α 1 , and the metal mass fraction, Z . This linear α 1 – Z relation has been calibrated up to ≈2 Z ⊙ , though higher metallicity environments are known to exist. We show that if the linear α 1 – Z relation extends to higher metallicities ([ Z ] ≳ 0.5), massive star formation is suppressed entirely. Alternatively, fragmentation efficiency may saturate beyond some metallicity threshold if gravitational collapse cascades rapidly enough. To model this behavior, we propose a logistic function describing the transition from metallicity-sensitive to metallicity-insensitive fragmentation regimes. We provide a user-friendly public code, pyIGIMF , which enables the instantaneous computation of the IGIMF theory with both linear and logistic α 1 – Z relations.