Rok Zaplotnik: Simulation of the observed Sagittarius stream bifurcation

Rok Zaplotnik, University of Ljubljana, Faculty of Mathematics and Physics. Dept. of Physics

Simulation of the observed Sagittarius stream bifurcation

We use the Sloan Digital Sky Survey Data Release 5 to study the tidal stream of the Sagittarius dwarf spheroidal galaxy in the area around the north Galactic Cap. Color and magnitude cut reveals the bifurcation of the Sagittarius stream. Two branches (A and B) are clearly visible, there is also evidence for a more distant wrap (C) well behind the A branch. Numerical simulation of Sagittarius stream shows that the dark Galactic halo must be close to spherical and that the initial mass of the Sagittarius dwarf spheroidal (Sgr dSph) was around $10^8M_\odot$. We can also predict how GAIA observations of Sagittarius stream proper motion will look like.