The mix of disky and boxy ellipticals |
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Authors: | Sadegh Khochfar Andreas Burkert |
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Institution: | 1. Max-Planck-Institut für Astronomie, K?nigstuhl 17, 69117, Heidelberg, Germany
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Abstract: | We use semi-analytical modelling of galaxy formation to predict the mix of elliptical galaxies with boxy and disky isophotes,
assuming they originated from major mergers of different mass ratios. Numerical simulations of merging spiral galaxies indicate
equal mass mergers leading to boxy and merger with a mass ratio of 3:1 to disky ellipticals. Assigning isophotal shapes to
elliptical galaxies in our model we find bright disky ellipticals being as frequent or more frequent as bright boxy ellipticals,
in contrast to observations which indicate that most of the bright ellipticals should be boxy. The precursors of bright ellipticals
in our model are mainly also ellipticals which merge with each other later. Assuming that the merger of two ellipticals results
in boxy ellipticals increases the fraction of bright boxy ellipticals. By defining a disky as a bulge dominated galaxy with
an additional disk mass of more than 20% the total baryonic mass, increases the fraction of low mass disky ellipticals and
reproduces the observed trend of a steep increase in the fraction of low mass disky ellipticals.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | simulation galaxies ellipticals |
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