A comment on the star density at the Galactic Centre, and the nature of infrared source sixteen

An analysis of high-resolution near infrared data shows that the power-law variation of star density |(ρ_(r) ∝~ \,r-1.8)| extends inwards to a central ‘core’ of radius |Rc 0.1 \,pc.| The core density is of order |10⁷ M_ \,pc⁻³,| and IRS 16 can be understood quantitatively as due to projection of this highly centrally condensed star distribution. The very high star density has a number of important implications for theories of the Galactic Centre, and makes it possible to explain the observed inward increase of gas velocity dispersion on models not containing a massive black hole. Dynamical evolution of the central core is very rapid; the core collapse time-scale for the model described here is ~ 109 yr. If a central constant-density ‘core’ has indeed been resolved, a rough upper limit to the mass of any black hole is |Mₕ Mc 10⁵ M_.|