Dissipationless mergers of elliptical galaxies and the evolution of the fundamental plane |
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| Authors: | Michael Boylan-Kolchin Chung-Pei Ma Eliot Quataert |
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| Institution: | Department of Physics, University of California, Berkeley, CA 94720, USA;Department of Astronomy, University of California, Berkeley, CA 94720, USA |
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| Abstract: | We carry out numerical simulations of dissipationless major mergers of elliptical galaxies using initial galaxy models that consist of a dark matter haloes and a stellar bulge with properties consistent with the observed fundamental plane. By varying the density profile of the dark matter haloes standard Navarro, Frenk & White (NFW) profile versus adiabatically contracted NFW profile], the global stellar to dark matter mass ratio and the orbit of the merging galaxies, we are able to assess the impact of each of these factors on the structure of the merger remnant. Our results indicate that the properties of the remnant bulge depend primarily on the angular momentum and energy of the orbit; for a cosmologically motivated orbit, the effective radius and velocity dispersion of the remnant bulge remain approximately on the fundamental plane. This indicates that the observed properties of elliptical galaxies are consistent with significant growth via late dissipationless mergers. We also find that the dark matter fraction within the effective radius of our remnants increases after the merger, consistent with the hypothesis that the tilt of the fundamental plane from the virial theorem is due to a varying dark matter fraction as a function of galaxy mass. |
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| Keywords: | methods: N-body simulations galaxies: evolution galaxies: fundamental parameters galaxies: structure dark matter |
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