The effects of the initial mass function on the chemical evolution of elliptical galaxies

De Masi, Carlo; Matteucci, F; Vincenzo, F

Abstract

We describe the use of our chemical evolution model to reproduce the abundance patterns observed in a catalogue of elliptical galaxies from the Sloan Digital Sky Survey Data Release 4. The model assumes ellipticals form by fast gas accretion, and suffer a strong burst of star formation followed by a galactic wind, which quenches star formation. Models with fixed initial mass function (IMF) failed in simultaneously reproducing the observed trends with the galactic mass. So, we tested a varying IMF; contrary to the diffused claim that the IMF should become bottom heavier in more massive galaxies, we find a better agreement with data by assuming an inverse trend, where the IMF goes from being bottom heavy in less massive galaxies to top heavy in more massive ones. This naturally produces a downsizing in star formation, favouring massive stars in largest galaxies. Finally, we tested the use of the integrated Galactic IMF, obtained by averaging the canonical IMF over the mass distribution function of the clusters where star formation is assumed to take place. We combined two prescriptions, valid for different SFR regimes, to obtain the Integrated Initial Mass Function values along the whole evolution of the galaxies in our models. Predicted abundance trends reproduce the observed slopes, but they have an offset relative to the data. We conclude that bottom-heavier IMFs do not reproduce the properties of the most massive ellipticals, at variance with previous suggestions. On the other hand, an IMF varying with galactic mass from bottom heavier to top heavier should be preferred.

Citation

De Masi, C., Matteucci, F., & Vincenzo, F. (2018). The effects of the initial mass function on the chemical evolution of elliptical galaxies. Monthly notices of the Royal Astronomical Society, 474(4), 5259-5271. https://doi.org/10.1093/mnras/stx3044

• Journal Article Type: Article
• Acceptance Date: Nov 17, 2017
• Online Publication Date: Nov 25, 2017
• Publication Date: Mar 11, 2018
• Deposit Date: Mar 12, 2022
• Publicly Available Date: Mar 28, 2022
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 474
• Issue: 4
• Pages: 5259-5271
• DOI: https://doi.org/10.1093/mnras/stx3044
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://hull-repository.worktribe.com/output/3948031