Andromeda XXV - A dwarf galaxy with a low central dark matter density

Abstract

Andromeda (And) XXV has previously been reported as a dwarf spheroidal galaxy (dSph) with little-to-no dark matter. However, the uncertainties on this result were significant. In this study, we nearly double the number of member stars and re-derive the kinematics and mass of And XXV. We find that And XXV has a systemic velocity of νr = -107.7 ± 1.0 kms-1 and a velocity dispersion of σ ν =3.7+1.2_-1.1 kms-1. With this updated velocity dispersion and a new literature measurement of the radial surface brightness profile, we derive a mass contained within the half-light radius of M(r