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A. Burkert, T. Naab (Max-Planck-Institut fuer Astronomie, Germany)
We present results of a large survey of high-resolution numerical simulations of merging disk galaxies and the formation of elliptical galaxies.
It is shown that the ellipticals have an internal structure that depends strongly on the adopted orbital parameters and the mass ratios of the progenitors. We find that
a) Equal mass mergers lead to boxy ellipticals.
b) Unequal mass mergers form disky ellipticals.
c)Prograde mergers form slightly anisotropic, rotating ellipticals.
d) Retrograde mergers form strongly anisotropic, slowly rotating ellipticals.
A comparison of the line-of-sight velocity distributions of the merger remnants with the observations shows that all (!) ellipticals with signatures of rotation must contain disk components which contain 10 system, in addition to the spheroidal component. The Hubble sequence therefore represents a sequence of varying disk-to-bulge (D/B) ratios. Spirals are characterized by D/B > 0.5, ellipticals by D/B < 0.3.
We will also present merger simulations of young spiral galaxies including gas which demonstrate that their gaseous component settles into the equatorial plane of the resulting elliptical where it forms tilted disks with structures as predicted by the comparison with the observations. These results provide interesting constraints for the cosmological merging of substructures in the Universe and the morphological transformation of galaxies.
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The author(s) of this abstract have provided an email address for comments about the abstract: burkert@mpia-hd.mpg.de