Dark Satellites and the Morphology of Dwarf Galaxies

Type Journal Article
Names Amina Helmi, L. V. Sales, E. Starkenburg, T. K. Starkenburg, C. A. Vera-Ciro, G. De Lucia, Y.-S. Li
Publication The Astrophysical Journal Letters
Volume 758
Pages L5
Journal Abbreviation The Astrophysical Journal Letters
Date October 1, 2012
DOI 10.1088/2041-8205/758/1/L5;
ISSN 0004-637X
URL http://adsabs.org/2012ApJ.758L.5H
Library Catalog labs.adsabs.harvard.edu
Abstract One of the strongest predictions of the ΛCDM cosmological model is the presence of dark satellites orbiting all types of galaxies. We focus here on the dynamical effects of such satellites on disky dwarf galaxies, and demonstrate that these encounters can be dramatic. Although mergers with M sat > Md are not very common, because of the lower baryonic content they occur much more frequently on the dwarf scale than for L * galaxies. As an example, we present a numerical simulation of a 20% (virial) mass ratio merger between a dark satellite and a disky dwarf (akin to the Fornax dwarf galaxy in luminosity) that shows that the merger remnant has a spheroidal morphology. Perturbations by dark satellites thus provide a plausible path for the formation of dSph systems. The transition from disky to the often amorphous, irregular, or spheroidal morphologies of dwarfs could be a natural consequence of the dynamical heating of hitherto unobservable dark satellites.
Tags GALAXIES: EVOLUTION, GALAXIES: INTERACTIONS, Galaxies: Dwarf, dark matter
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