Kinematics of Tidal Debris from Omega Centauri's Progenitor Galaxy

摘要

We present the kinematic properties of a tidally disrupted dwarf galaxy inthe Milky Way, based on the hypothesis that its central part once contained themost massive Galactic globular cluster, omega Cen. Dynamical evolution of aself-gravitating progenitor galaxy that follows the present-day and likely pastorbits of omega Cen is calculated numerically and the kinematic nature of theirtidal debris is analyzed, combined with randomly generated stars comprisingspheroidal halo and flat disk components. We show that the retrograde rotationof the debris stars at $sim -100$ km/s accords with a recently discovered,large radial velocity stream at $sim 300$ km/s towards the Galactic longitudeof $sim 270^circ$. These stars also contribute, only in part, to a reportedretrograde motion of the outer halo at the North Galactic Pole. The prospectsfor future debris searches and the implications for the early evolution of theGalaxy are briefly presented.