2013/01/30 by Kenji Bekki, Gerhardt R. Meurer · 9 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Initial mass function #Interstellar medium #Star (game theory) #Star formation #Stellar evolution #Stellar mass #Variation (astronomy) #astro-ph.CO
paper · pdf · doi:10.1088/2041-8205/765/1/l22
published in The Astrophysical Journal Letters 765(1), L22 (IOP Publishing) · 14pages, 5figures, accepted for publication in ApJL
arxiv created 2013/01/30 · openalex publication_date 2013/02/19 · arxiv updated 2015/06/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We investigate the time evolution and spatial variation of the stellar initial mass function (IMF) in star-forming disk galaxies by using chemodynamical simulations with an IMF model depending both on local densities and metallicities ([Fe/H]) of the interstellar medium (ISM). We find that the slope (α) of a power-law IMF ( N ( m )∝ m −α ) for stellar masses larger than 1 M ☉ evolves from the canonical Salpeter IMF (α ≈ 2.35) to be moderately top-heavy one (α ≈ 1.9) in the simulated disk galaxies with starbursts triggered by galaxy interaction. We also find that α in star-forming regions correlates with star formation rate densities (Σ SFR in units of M ☉ yr −1 kpc −2 ). Feedback effects of Type Ia and II supernovae are found to prevent IMFs from being too top-heavy (α < 1.5). The simulation predicts α ≈ 0.23log Σ SFR + 1.7 for log Σ SFR ⩾ −2 (i.e., more top-heavy in higher Σ SFR ), which is reasonably consistent with corresponding recent observational results. The present study also predicts that inner regions of starburst disk galaxies have smaller α and thus are more top-heavy ( d α/ dR ∼ 0.07 kpc −1 for R ⩽ 5 kpc). The predicted radial α gradient can be tested against future observational studies of the α variation in star-forming galaxies.