The slope of the mass profile and the tilt of the fundamental plane in early-type galaxies

Understand

We present a survey, using the Chandra X-ray observatory, of the central gravitating mass profiles in a sample of 10 galaxies, groups and clusters, spanning ~2 orders of magnitude in virial mass.

• We find the total mass distributions from ~0.2--10Re, where Re is the optical effective radius of the central galaxy, are remarkably similar to powerlaw density profiles.
• The negative logarithmic slope of the mass density profiles, alpha, systematically varies with Re, from alpha=2, for systems with Re~4kpc to alpha=1.2 for systems with Re>30kpc.
• Departures from hydrostatic equilibrium are likely to be small and cannot easily explain this trend.