EVOLUTION OF THE HIGH-MASS END OF THE STELLAR INITIAL MASS FUNCTIONS IN STARBURST GALAXIES

Journal Article · Fri Mar 01 04:00:00 EST 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/765/1/L22· OSTI ID:22130847

Bekki, Kenji; Meurer, Gerhardt R. ^[1]

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1. ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

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 ({alpha}) of a power-law IMF (N(m){proportional_to}m {sup -{alpha}}) for stellar masses larger than 1 M{sub Sun} evolves from the canonical Salpeter IMF ({alpha} Almost-Equal-To 2.35) to be moderately top-heavy one ({alpha} Almost-Equal-To 1.9) in the simulated disk galaxies with starbursts triggered by galaxy interaction. We also find that {alpha} in star-forming regions correlates with star formation rate densities ({Sigma}{sub SFR} in units of M{sub Sun} yr{sup -1} kpc{sup -2}). Feedback effects of Type Ia and II supernovae are found to prevent IMFs from being too top-heavy ({alpha} < 1.5). The simulation predicts {alpha} Almost-Equal-To 0.23log {Sigma}{sub SFR} + 1.7 for log {Sigma}{sub SFR} {>=} -2 (i.e., more top-heavy in higher {Sigma}{sub SFR}), which is reasonably consistent with corresponding recent observational results. The present study also predicts that inner regions of starburst disk galaxies have smaller {alpha} and thus are more top-heavy (d{alpha}/dR {approx} 0.07 kpc{sup -1} for R {<=} 5 kpc). The predicted radial {alpha} gradient can be tested against future observational studies of the {alpha} variation in star-forming galaxies.

• OSTI ID: 22130847
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 765; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DENSITY
EVOLUTION
FEEDBACK
GALAXIES
INTERACTIONS
LUMINOSITY
MASS
SIMULATION
SUPERNOVAE