Mass loss from galaxies: feeding the IGM, recycling in the IGM

As a result of internal processes or environmental effects like ram-pressure stripping or collisions, galaxies lose a significant part of their stellar and gaseous content. Whereas the impact of such stripping on galaxy evolution has been well studied, much less attention has been given to the fate of the expelled material in the intergalactic or intracluster medium (IGM/ICM). Observational evidence exists showing that a fraction of the injected matter is actually recycled to form a new generation of galaxies, such as the Tidal Dwarf Galaxies discovered near numerous interacting systems. Using a set of multiwavelength data, we are now able to roughly analyze the processes pertaining to their formation: from an instability in the HI clouds, through the formation of molecular gas, and to the onset of star formation.