The galaxy-wide initial mass function of dwarf late-type to massive early-type galaxies

Weidner, C.; Vazdekis, A.; Pflamm-Altenburg, J.; Kroupa, P.
Referencia bibliográfica

Monthly Notices of the Royal Astronomical Society, Volume 436, Issue 4, p.3309-3320

Fecha de publicación:
12
2013
Número de autores
4
Número de autores del IAC
2
Número de citas
86
Número de citas referidas
78
Descripción
Observational studies are showing that the galaxy-wide stellar initial mass function (IMF) is 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 M⊙ 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 mass-to-light ratios as a result of the overabundance of stellar remnants compared to a stellar population that formed with an invariant canonical stellar IMF. For the Milky Way, the IGIMF yields very good agreement with the disc- and the bulge IMF determinations. Our conclusions are that purely stochastic descriptions of star formation on the scales of a parsec 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 β 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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