Warm dark matter models in particle physics and cosmology

We study the so called Warm Dark Matter models for which the formation of cosmic structure on sub galactic scales is substantially suppressed in comparison to the Cold Dark Matter case Such models are motivated by persistent discrepancies between astrophysical observations and the results of structure formation simulations in CDM We discuss astrophysical bounds on such dark matter models and consider several particular scenarios with a sterile neutrino and a light gravitino dark matter We also discuss an ultra light scalar field as