Are Omega Centauri and G1 like massive globular clusters the remnant cores of infalling dwarf galaxies? -- Dynamical constraints

Abstract

We simulate the result of orbital decay for a dwarf satellite galaxy in a disk galaxy potential. The peeling-off of the satellite by the strong tidal field within the disk of the host galaxy quickly reduces the satellite's mass, and drastically slows down the decaying of the orbit. The result is generally a cluster on a large halo orbit, like the M54 cluster of the Sagittarius galaxy in the Milky Way and the massive G1 cluster in outer halo of M31. It is generally challenging for this mechanism to deliver globular cluster-mass objects to the observed very close-in orbit of Omega Cen unless the dwarf galaxy was born within a few scale lengths of the Galactic disk.