Heart of Darkness - How galactic dynamics suppress star formation in galaxy spheroids
Jindra Gensior
Thursday December 4th, 10:35
Most galaxy formation simulations adopt a subgrid model for star formation inspired by the Kennicutt-Schmidt relation, i.e. one that depends only on the gas density. However, recent observations of early-type galaxies and galaxy bulges show that their star formation rates fall below the predictions of density-based star formation relations. This implies that additional physical dependences, which are not accurately captured by density-based relations, play an important role in the star formation process. This agrees with predictions made by current theories of star formation, which indicate a dependence of the star formation efficiency on the virial parameter of the gas. I will present hydrodynamic simulations of (bulge-dominated) disc galaxies, run with the moving-mesh code Arepo, with a new subgrid model for star formation, which captures the influence of galactic dynamics on the star formation efficiency via a dependence on the virial parameter. I show that galactic dynamics suppress star formation in the central regions of galaxies relative to their discs, with the suppression increasing the more the bulge dominates. Furthermore, using a physically motivated star formation subgrid model affects the ISM structure within the galaxy. These results represent an important step towards obtaining a fundamental understanding of the observed connection between the morphology, dynamics and star formation efficiency in galaxy spheroids.