Supernova feedback

Supernovae eject not only thermal energy that serves to suppress star formation, but they also produce heavy elements to enhance star formation. Therefore, those processes have to be solved simultaneously. Supernova feedback, in particular hypernova feedback (Kobayashi et al. 2007), generates galactic winds from present-day less-massive galaxies (Fig. 2) and heavy elements are ejected from galaxies into the intergalactic medium. Supernova feedback plays an essential role in solving i) the angular momentum problem (Steinmetz & Navarro 1999), wherein the number and sizes of spiral galaxies in simulations are smaller than those observed, and ii) the missing satellite problem (Moore et al. 1999), in which the predicted number of satellite galaxies are much larger than those observed. These touch on a big question of galactic astronomy, the origin of the galactic morphology. How did spiral and elliptical galaxies form?

The time evolution of the formation of an isolated disk galaxy in a halo of mass of 10^10/h Msun. The black points represent star particles, while the gas particles are colour-coded according to their temperature. Each panel is 20 kpc on a side. The upper row shows face-on projections, the lower row gives edge-on views. Watch the movie on this link.