COLLISION TOMOGRAPHY: PHYSICAL PROPERTIES OF POSSIBLE PROGENITORS OF THE ANDROMEDA STELLAR STREAM

To unveil a progenitor of the Andromeda Giant Stellar Stream, we investigate the interaction between an accreting satellite galaxy and the Andromeda Galaxy using an N-body simulation. We perform a comprehensive exploration of the properties of the progenitor dwarf galaxy, using 247 models of varying mass, mass distribution, and size. We show that the binding energy of the progenitor is the crucial parameter in reproducing the Andromeda Giant Stellar Stream and the shell-like structures surrounding the Andromeda Galaxy. As a result of the simulations, the progenitor must satisfy a simple scaling relation between the core radius, the total mass and the tidal radius. Using this relation, we successfully constrain the physical properties of the progenitors to have masses ranging from 5 x 10(8) M-circle dot to 5 x 10(9) M-circle dot and central surface densities. around 10(3) M-circle dot pc(-2). A detailed comparison between our result and the nearby observed galaxies indicates that possible progenitors of the Andromeda Giant Stellar Stream include a dwarf elliptical galaxy, a dwarf irregular galaxy, and a small spiral galaxy.