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arXiv · astro-ph/9611104

The Shapes and Ages of Elliptical Galaxies

Roelof S. de Jong·Roger L. Davies
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Abstract

In this paper we investigate the relation between the detailed isophotal shape of elliptical galaxies and the strength of the H beta absorption in their spectra. We find that disky galaxies have higher H beta indices. Stellar population synthesis models show that the H beta line is a good age indicator, hence disky galaxies tend to have younger mean ages than boxy galaxies. We show that the observed trend can be brought about by a contaminating young population, which we associate with the disky component. This population need only account for a small fraction of the total mass, for example if a contaminating population of age of 2 Gyrs is superimposed on an old (12 Gyr) elliptical galaxy, then the observed trend can be explained if it contributes only 10% to the total mass. The size of this effect is consistent with the estimates of disk-to-total light ratios from surface photometry.

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Roelof S. de Jong, Roger L. Davies. 1996-11-13. The Shapes and Ages of Elliptical Galaxies. https://doi.org/10.1093/mnras%2F285.1.l1

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