Abstract
Galaxy formation is a two-step process . The gravitational instability of primordial density fluctuations forms dark matter halos. The collapse of gas into matter halos forms luminous galaxies. Semi-analytical modeling treats these two steps separately. First, merge trees are constructed to track the hierarchical growth of dark matter halos. Then, analytical models are used to describe the evolution of baryons in dark matter halos. We will describe the context in which this approach was developed, the main assumptions and the observations that semi-analytical models seek to explain. We conclude with a presentation of some recent results.
