[Seminar] (Jan 12 2016) by Takashi Okamoto on <Small-scale problems of CDM and baryonic solutions to them>

* Abstract: The Lambda-dominated cold dark matter model provides excellent fits to observations of the cosmic microwave background, large-scale structure of the Universe, type Ia supernovae, and so on. On small scales, however, the Lambda-CDM model has many difficulties. The disagreement between theory and observations are the largest on the scale of dwarf galaxies. These problems are, however, pointed out mainly by simulations that only consider dark matter. I review the small-scale problems of CDM and then I show how inclusion of baryons (gas and stars) solves these problems in cosmological simulations of galaxy formation with a particular emphasis on the effect of feedback (gas heating due to radiation and supernova explosions). I also discuss remaining problems that are difficult to solve by baryonic processes.