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arXiv · 1309.6634

The galaxy-wide IMF of dwarf late-type to massive early-type galaxies

Carsten Weidner·Pavel Kroupa·Jan Pflamm-Altenburg·Alexandre Vazdekis
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Abstract

Observational studies are showing that the galaxy-wide stellar initial mass function are top-heavy in galaxies with high star-formation rates (SFRs). Calculating the integrated galactic stellar initial mass function (IGIMF) as a function of the SFR of a galaxy, it follows that galaxies which have or which formed with SFRs > 10 Msol yr^-1 would have a top-heavy IGIMF in excellent consistency with the observations. Consequently and in agreement with observations, elliptical galaxies would have higher M/L ratios as a result of the overabundance of stellar remnants compared to a stellar population that formed with an invariant canonical stellar initial mass function (IMF). For the Milky Way, the IGIMF yields very good agreement with the disk- and the bulge-IMF determinations. Our conclusions are that purely stochastic descriptions of star formation on the scales of a pc and above are falsified. Instead, star formation follows the laws, stated here as axioms, which define the IGIMF theory. We also find evidence that the power-law index beta of the embedded cluster mass function decreases with increasing SFR. We propose further tests of the IGIMF theory through counting massive stars in dwarf galaxies.

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Carsten Weidner, Pavel Kroupa, Jan Pflamm-Altenburg, Alexandre Vazdekis. 2013-10-17. The galaxy-wide IMF of dwarf late-type to massive early-type galaxies. https://doi.org/10.1093/mnras%2Fstt1806

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