Dark Matter Contraction and the Stellar Content of Massive Early-type Galaxies: Disfavoring "Light" Initial Mass Functions

Auger, M. W., Treu, T., Gavazzi, R., Bolton, A. S., Koopmans, L. V. E. & Marshall, P. J., 1-Oct-2010, In : Astrophysical Journal Letters. 721, 2, p. L163-L167 5 p.

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We use stellar dynamics, strong lensing, stellar population synthesis models, and weak lensing shear measurements to constrain the dark matter (DM) profile and stellar mass in a sample of 53 massive early-type galaxies. We explore three DM halo models (unperturbed Navarro, Frenk, and White (NFW) halos and the adiabatic contraction models of Blumenthal and Gnedin) and impose a model for the relationship between the stellar and virial mass (i.e., a relationship for the star formation efficiency as a function of halo mass). We show that, given our model assumptions, the data clearly prefer a Salpeter-like initial mass function (IMF) over a lighter IMF (e.g., Chabrier or Kroupa), irrespective of the choice of DM halo. In addition, we find that the data prefer at most a moderate amount of adiabatic contraction (Blumenthal adiabatic contraction is strongly disfavored) and are only consistent with no adiabatic contraction (i.e., an NFW halo) if a mass-dependent IMF is assumed, in the sense of a more massive normalization of the IMF for more massive halos.

Original languageEnglish
Pages (from-to)L163-L167
Number of pages5
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 1-Oct-2010


  • dark matter, galaxies: elliptical and lenticular, cD, galaxies: halos, galaxies: structure, LENS ACS SURVEY, FUNDAMENTAL PLANE, SPHERICAL GALAXIES, INTERNAL STRUCTURE, DENSITY PROFILES, EVOLUTION, MODEL, HALOES, ENVIRONMENT, FRACTIONS

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