Journal Article

A possible theoretical explanation of metallicity gradients in elliptical galaxies

Agostino Martinelli, Francesca Matteucci and Sergio Colafrancesco

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 298, issue 1, pages 42-52
Published in print July 1998 | ISSN: 0035-8711
Published online July 1998 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-8711.1998.01544.x
A possible theoretical explanation of metallicity gradients in elliptical galaxies

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Abstract

Models of chemical evolution of elliptical galaxies taking into account different escape velocities at different galactocentric radii are presented. As a consequence of this, the chemical evolution develops differently in different galactic regions; in particular, we find that the galactic wind, powered by supernovae (of Type II and I) starts, under suitable conditions, in the outer regions and successively develops in the central ones. The star formation is assumed to stop after the onset of the galactic wind in each region. The main result found in the present work is that this mechanism is able to reproduce metallicity gradients, namely the gradients in the Mg2 index, in good agreement with observational data. We also find that in order to honour the constant [〈Mg/Fe〉] ratio with galactocentric distance, as inferred from metallicity indices, a variable initial mass function as a function of galactocentric distance is required. This is only a suggestion, as trends on abundances inferred purely from metallicity indices are still uncertain.

Keywords: galaxies: abundances; galaxies: elliptical and lenticular; cD; galaxies: evolution; galaxies: formation

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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