Kyu-Hyun Chae, Mariangela Bernardi, Andrey V. Kravtsov
We present an unprecedented statistical set of global dynamical models of 2,118 nearly spherical Sloan Digital Sky Survey galaxies with new measurements of their structural parameters combined with published empirical relations among galaxy and halo parameters. The models show that the slope of the three-dimensional total density profiles has a characteristic S-shape pattern as a function of log radius. At radii 0.1R_eff < r < R_eff, where R_eff is the effective (i.e. projected half-light) radius, we find a tight correlation as =(1.826+/-0.011)+(-5.36+/-0.16) where and are respectively the mean slopes of the total density and velocity dispersion profiles, which leads to a super-isothermal = 2.18+/-0.04 for =-0.066+/- 0.008 in observed elliptical galaxies. Our results suggest that the isothermal profile is not a universal profile for elliptical galaxies but the pseudo-phase-space density Q(r)=rho(r)/sigma_r(r)^3, where rho(r) is the total density profile and sigma_r(r) is the radial stellar velocity dispersion profile, may well have a universal profile. We find that the slope of the Q(r) profile is ~ -1.874, remarkably similar to the corresponding slope of dark matter halo profile in dissipationless N-body simulations.
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http://arxiv.org/abs/1305.5471
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