Hide and seek in the halo of the Milky Way

With the fast development of observations of the Gaia satellite, we will soon be able to obtain 3D positions and velocities of individual stars in the Milky Way. In Chapter 2 of this thesis, we have established the ability and limitations of recovering stellar streams in datasets with full phase space information using a phase space halo  finder, which is named ROCKSTAR (Behroozi et al. 2013). With a slightly modified algorithm, we can recover typically 30 to 40 percent of the stream progenitors with high purity, typically above 0.8. In Chapter 3, we have studied how a ground-based telescope can help with studying the merging history of the Milky Way. We found the RGB stars are the better tracers, with which the fraction of the detectable progenitors increases linearly with coverage. For a coverage of 10,000 s.q. deg. this fraction is larger than 0.5.

Using the first data release of Gaia mission, in Chapter 4 we introduced three algorithms which use only the positions on the sky and apparent magnitude of stars. We found that even with only the limited information, the methods are able to identify 110 known objects and more than 200 new candidates.

Dissertation: http://hdl.handle.net/11370/5bd9b720-9229-4688-a9eb-1d0e1beb304d