Mon. Not. R. Astron. Soc., 483, 2217-2235 (2019/February-3)
Is the IMF in ellipticals bottom-heavy? Clues from their chemical abundances.
DE MASI C., VINCENZO F., MATTEUCCI F., ROSANI G., LA BARBERA F., PASQUALI A. and SPITONI E.
Abstract (from CDS):
We tested the implementation of different initial mass functions (IMFs) in our model for the chemical evolution of ellipticals, with the aim of reproducing the observed relations of [Fe/H] and [Mg/Fe] abundances with galaxy mass in a sample of early-type galaxies selected from the SPIDER-SDSS catalogue. Abundances in the catalogue were derived from averaged spectra, obtained by stacking individual spectra according to central velocity dispersion, as a proxy of galaxy mass. We tested IMFs already used in a previous work, as well as two new models, based on low-mass tapered ('bimodal') IMFs, where the IMF becomes either (1) bottom-heavy in more massive galaxies, or (2) is time-dependent, switching from top-heavy to bottom-heavy in the course of galactic evolution. We found that observations could only be reproduced by models assuming either a constant, Salpeter IMF, or a time-dependent distribution, as other IMFs failed. We further tested the models by calculating their M/L ratios. We conclude that a constant, time-independent bottom-heavy IMF does not reproduce the data, especially the increase of the [α/Fe] ratio with galactic stellar mass, whereas a variable IMF, switching from top to bottom-heavy, can match observations. For the latter models, the IMF switch always occurs at the earliest possible considered time, i.e. tswitch = 0.1 Gyr.
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
galaxies: abundances - galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: luminosity function, mass function
View the reference in ADS
To bookmark this query, right click on this link: simbad:2019MNRAS.483.2217D and select 'bookmark this link' or equivalent in the popup menu