摘要
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 linearα_1-Z relation has been calibrated up to≈2Z_☉,though higher metallicity environments are known to exist.We show that if the linearα_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 metallicityinsensitive fragmentation regimes.We provide a user-friendly public code,pyIGIMF,which enables the instantaneous computation of the IGIMF theory with both linear and logisticα_1-Z relations.
基金
support of the National Natural Science Foundation of China(NSFC,grant Nos.1251101411,12041305,12173016,1257030642,12533003,and 12203021)
science research grants from the China Manned Space Project with NOs.CMS-CSST-2021-A08(IMF),CMS-CSST-2021-A07
Program for Innovative Talents
Entrepreneur in Jiangsu
supported by the Fundamental Research Funds for the Central Universities,No.KG202502
support from the Jiangsu Funding Program for Excellent Postdoctoral Talent under grant No.2022ZB54
the Fundamental Research Funds for the Central Universities under grant No.0201/14380049
support through the DAAD-Eastern-European Exchange program between Bonn and Prague。
