  We complete the analysis of part I in this series (Ref.
\cite{Stotyn:2013yka}) by numerically constructing boson stars in 2+1
dimensional Einstein gravity with negative cosmological constant, minimally
coupled to a complex scalar field. These lower dimensional boson stars have
strikingly different properties than their higher dimensional counterparts,
most noticeably that there exists a finite central energy density, above which
an extremal BTZ black hole forms. In this limit, all of the scalar field
becomes enclosed by the horizon; it does not contract to a singularity, but
rather the origin remains smooth and regular and the solution represents a
spinning boson star trapped inside a degenerate horizon. Additionally, whereas
in higher dimensions the mass, angular momentum, and angular velocity all
display damped harmonic oscillations as functions of the central energy
density, in $D=3$ these quantities change monotonically up to the bound on the
central energy density. Some implications for the holographic dual of these
objects are discussed and it is argued that the boson star and extremal BTZ
black hole phases are dual to a spontaneous symmetry breaking at zero
temperature but finite energy scale.
