Maximum Density of Baryons on Parsec and Larger Scales

Norman Murray


I will show that observations of stellar systems with masses ranging from 10,000 to 10^{12} solar masses have a maximum density. The upper envelope of the density at the half light radius scales as the inverse mass to the four fifths power. The density at a fixed physical radius, say ten parsecs, is also described by an upper envelope; the density at ten parsecs less than 10^{-17} g/cm3, or 105 solar masses/pc3. I will discuss possible explanations for this maximum density.