0 Assigned ID: 361 ----- Attempting Submission 1 (Fri Apr 08 02:59:51 GMT 2016) ----- Among the most fundamental predictions of LCDM cosmology is the existence of a large number of dark subhalos in and around galaxies, most of which should be entirely devoid of stars. Confirming the existence of this substructure stands among the most important empirical challenges in modern cosmology. The goal of this proposal is to make robust LCDM predictions for dark halo substructure using high-resolution cosmological simulations that explicitly include the effects of baryons via a fast hybrid N-body method as well as full hydrodynamical runs. Observational studies of strong gravitational lensing systems using HST and other instruments have begun to detect substructures with masses approaching those where halos may be entirely dark. There is real hope that similar studies can detect and quantify subhalos with masses 100 times smaller. Moreover, the number of suitable lenses is expected to grow substantially in coming years. Stellar streams around the Milky Way provide an independent means of detecting substructure. The number of cold stellar streams is too expected to grow as surveys like LSST come on line. While we are poised for phase-change in our ability to detect and quantify substructure, the current state of theoretical predictions is far behind. The vast majority of predictions include only dark matter and therefore neglect the destructive effect of central galaxies -- an effect that is know to reduce substructure significantly in the cores of halos, the very regions where observations are most sensitive. Our simulations will overcome this deficiency and provide the predictions needed to accurately interpret observational results. Intergalactic Medium and Cosmology Galaxies 0 Regular false false true SUPPORTED