Collision tomography: Physical properties of possible progenitors of the Andromeda stellar stream

TL;DR

This study uses N-body simulations to identify the physical properties of potential progenitors of the Andromeda Giant Stellar Stream, revealing key parameters like mass and density that match observed structures.

Contribution

It introduces a comprehensive parameter study linking progenitor properties to stream features, constraining progenitor types and their physical characteristics.

Findings

Progenitor mass range: 5×10^8 to 5×10^9 solar masses

A simple scaling relation between core radius, mass, and tidal radius

Possible progenitors include dwarf elliptical, dwarf irregular, and small spiral galaxies

Abstract

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. A comprehensive parameter study with 247 models is performed by varying size and mass distribution of the progenitor dwarf galaxy. 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 mass ranging from $5\times10^8 M_\odot$ to $5\times10^9 M_\odot$ and central surface density around $10^3\, M_\odot\, \mathrm{pc}^{-2}$. 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.