Dwarf spheroidal kinematics with large radial velocity samples

Abstract

I present a large sample of precise ($\pm2$ km/s) stellar radial velocities obtained to serve as kinematic tracers in Milky Way dwarf spheroidal (dSph) satellite galaxies. This includes velocities for $\sim$750 member stars spanning several core radii in the Sculptor dSph, and $\sim$400 member stars extending out to the nominal tidal radius of the Fornax dSph. The resulting radial velocity dispersion profiles are flat, with no evidence for a sharp decrease in the velocity dispersion at large galactocentric radius in either Sculptor of Fornax. Application of a non-parametric method for estimating the radial mass distributions gives results consistent with mass determinations from classical analyses, with lower limits of $[M/L]_V \,{\sim} 7$ for Fornax and $[M/L]_V\,{\sim}4$ for Sculptor.