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| Paper: |
Upper End IMF Variations Deduced from HI-Selected Galaxies |
| Volume: |
440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function? |
| Page: |
189 |
| Authors: |
Meurer, G. R. |
| Abstract: |
Much of our understanding of modern astrophysics rest on the notion
that the Initial Mass Function (IMF) is universal. Our observations
of a sample of HI-selected galaxies in the light of Hα and the
far-ultraviolet (FUV) challenge this result. The flux ratio FHα/fFUV from these star formation tracers shows strong
correlations with surface-brightness in Hα and the R band:
Low Surface Brightness (LSB) galaxies have lower FHα/fFUV ratios compared to High Surface Brightness
(HSB) galaxies as well as compared to expectations from equilibrium
models of constant star formation rate (SFR) using commonly favored
IMF parameters. I argue against recent claims in the literature that
attribute these results to errors in the dust corrections, the
micro-history of star formation, sample issues or escaping ionizing
photons. Instead, the most plausible explanation for the correlations
is the systematic variations of the upper mass limit and/or the slope
of the IMF. I present a plausible physical scenario for producing the
IMF variations, and suggest future research directions. |
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