Dark influences: the impact of dark satellites on dwarf galaxies

The structure in our Universe is thought to have formed in a hierarchical fashion. This means that galaxies, from small to large, grow through accretion, and through interactions and mergers with other galaxies. Within the concordance LCDM cosmological framework, galaxies are embedded in dark matter halos, but the vast majority of the smallest halos have likely been unable to host a galaxy. Detecting these small, star-less but very numerous halos is very important as it may provide novel clues to the nature of the dark matter, and may be possible through their gravitational effects on luminous matter. In this talk, I present a suite of simulations studying the effects of dark satellites on dwarf galaxies. We find that these interactions can lead to the formation of irregular, starbursting, and spheroidal systems. Furthermore, we characterize the effects of the dark satellites quantitatively through morphological and kinematical indicators to aid their observational identification. Our models predict that a significant fraction of the dwarf galaxies at the present day likely has recently experienced such an interaction. Therefore, interactions with smaller dark matter halos may well contribute to the diversity of the dwarf galaxy population.

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