This paper presents a comprehensive model for the tidal destruction of the Sagittarius dwarf galaxy. This model allows us to deduce not only the orbital history of Sagittarius, but also more fundamental parameters such as the mass and shape of the Milky Way and its dark matter halo.

In particular, our paper combined previous detections of Sagittarius tidal debris with new kinematic studies and all-sky 2MASS data to produce the first truly comprehensive model of the system. Our numerical model is publicly available so that it may be readily tested against future data.

It is the first paper to fit a numerical model to the comprehensive, all-sky view of Sagittarius provided by 2MASS. As such, the model is better constrained than previous models, which were based on much sparser data.

The Two Micron All-Sky Survey (2MASS) has looked at stars in the infrared and found that the Sagittarius dwarf galaxy (which orbits our own, much larger Milky Way Galaxy) is being torn by tidal forces into long, thin streams which wrap entirely around the Milky Way.

Our paper uses the exceptional new view of these streams to develop a numerical model for the tidal destruction which allows us to determine the size, shape, and mass content of the Milky Way.

The astrophysicists Kathryn Johnston (Wesleyan) and Steve Majewski (UVA) have worked in the field of Galactic stellar streams for a number of years, Kathryn focusing primarily on numerical simulations and Steve on observational studies of Galactic satellites. As a student and newcomer to the field, I was fortunate to have the opportunity to work with them both to combine numerical simulations with the newly observed 2MASS tidal stream data.

As with any numerical study, we frequently faced challenges attempting to find a unique combination of parameters which produced the best fit to the data. While these were overcome with careful analysis, we found that two different observational constraints favored slightly different models for the shape of the Galactic halo. Our inability to resolve this discrepancy highlights new and interesting areas to explore as further data become available.