http://arxiv.org/abs/1401.4742
Early type galaxies, ellipticals and S0’s, have two distinct core density profiles, either a power law or nearly flat in projection. The two core types are distributed with substantial overlap in luminosity, radius, mass and velocity dispersion, however, the cores separate into two distinct distributions in their coarse grain phase density, Q_0 = rho/sigma^3,suggesting that dynamical processes played a dominant role in their origin. The transition phase density separating the two elliptical types is approximately 0.003 M_sun pc^-3 km^-3 s^3,. The Q_0*M_c^2 vs M_c diagram shows that globular clusters, nuclear star clusters and power-law cores fall on what is likely a “collisional” sequence of inspiralling globular clusters. on which the relative core mass excess varies as the bulk stellar mass to the -0.34+/-0.08 power, close to predictions, albeit with a correlation coefficient of -0.46. Both power-law and cored galaxies lie on a single sequence of approximately Q_0 ~r_c^-2.2, suggesting that transport processes, such as two-body relaxation and globular cluster inspiral, were at some stage important. For an enriched high redshift globular cluster population the maximum mass that can spiral in over a Hubble time is very close to the mass at the transition phase density.
Tue, 21 Jan 14
47/91
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