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03/27/14 Antonela Monachesi SO/NOAO Joint Colloquium Series


Antonela Monachesi, Michigan

Testing Stellar Halo Formation Models with the GHOSTS Survey

Models of galaxy formation predict that properties of stellar halos, such as degree of substructure, shapes, and mean properties of their stellar populations as a function of galactocentric distance, are important probes of the physics of stellar halo formation. Different scenarios predict different characteristic properties. However, in all scenarios a substantial halo-to-halo scatter is predicted, owing to stochasticity in galaxies' merger histories. Currently, only few detailed observations of stellar halos are available, mainly for the MW and M31. Therefore, a systematic enlargement of this sample is needed to understand both the range of possible halo properties and what a 'typical' halo looks like. The Galaxy Halos, Outer disks, Substructure, Thick disks and Star clusters (GHOSTS) survey is the largest study of the resolved stellar populations in the outskirts of disk galaxies to date and its observations offer a direct test of model predictions. I will present recent results from the GHOSTS observations, in particular the stellar halo color profiles out to ~50-70 kpc along the minor axis of nearby Milky Way-like galaxies. In addition, I will report the discovery of a faint and very isolated dwarf galaxy in one of the GHOSTS fields.

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