Dwarf galaxies in observed and simulated galaxy clusters (Ludwig Biermann Award Lecture 2011)

Galaxy clusters are populated by thousands of low-mass galaxies, with hundreds of them already within stellar masses of 10⁸≤M_\star ≤10^9.5 M_⊙ and magnitudes of {-16≤M_r ≤-19} mag. While objects in this regime are commonly termed ``dwarfs'', they are not as faint and diffuse as many of the known Milky Way satellites. Their observed complexity, particularly regarding the dominant early-type dwarf population, is still poorly understood and requires models and simulations of environmental influence on dwarfs. Studying cluster dwarf galaxies at the current time is motivated by two facts: (i) for nearby clusters, multicolour observational samples exist that are complete in the above luminosity range and cover a substantial portion of the cluster; (ii) state-of-the-art semi-analytic models based on high-resolution N-body simulations, reaching down to dwarf masses, have recently become available. Here I show how comparisons of models and observations can serve as a tool for studying the evolutionary history of low-mass galaxy populations in today's clusters.

Partly based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (programme 077.B-0785).}