Simple interpolation functions for the galaxy-wide stellar initial mass function and its effects in early-type galaxies
Abstract
The galaxy-wide stellar initial mass function (IGIMF) of a galaxy is thought to depend on its star formation rate (SFR). Using a catalogue of observational properties of early-type galaxies (ETGs) and a relation that correlates the formation time-scales of ETGs with their stellar masses, the dependencies of the IGIMF on the SFR are translated into dependencies on more intuitive parameters like present-day luminosities in different passbands.
It is found that up to a luminosity of approximately 10(9) L-circle dot (quite independent of the considered passband), the total masses of the stellar populations of ETGs are slightly lower than expected from the canonical stellar initial mass function (IMF). However, the actual mass of the stellar populations of the most luminous ETGs may be up to two times higher than expected from a simple stellar population model with the canonical IMF.
The variation of the IGIMF with the mass of ETGs is presented here also as convenient functions of the luminosity in various passbands.