Systematic variations of central mass density slopes in early-type galaxies

Abstract

We study the total density distribution in the central regions (~ 1 effective radius, $R_e$) of early-type galaxies (ETGs), using data from SPIDER and $\mathrm{ATLA}{\mathrm{S}}^{3D}$. Our analysis extends the range of galaxy stellar mass ($M_{\star }$) probed by gravitational lensing, down to ~ $10^{10}{\mathrm{M}}_{\odot }$. We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter (DM) halo profile (i.e. NFW, NFW-contracted, and Burkert profiles), and leaving stellar mass-to-light ($M_{\star }/L$) ratios as free fitting parameters to the data. For all plausible halo models, the best-fitting $M_{\star }/L$, normalized to that for a Chabrier IMF, increases systematically with galaxy size and mass. For an NFW profile, the slope of the total mass profile is non-universal, independently of several ingredients in the modeling (e.g., halo contraction, anisotropy, and rotation velocity in ETGs). For the most massive ($M_{\star }$ ~ $10^{11.5}{M}_{\odot }$) or largest ($R_{\mathrm{e}}$ ~ $15\mathrm{kpc}$) ETGs, the profile is isothermal in the central regions (~$R_{\mathrm{e}}/2$), while for the low-mass ($M_{\star }$ ~ $10^{10.2}{M}_{\odot }$) or smallest ($R_{\mathrm{e}}$ ~ $0.5\mathrm{kpc}$) systems, the profile is steeper than isothermal, with slopes similar to those for a constant-$M/L$ profile. For a steeper concentration-mass relation than that expected from simulations, the correlation of density slope with galaxy mass tends to flatten, while correlations with $R_{\mathrm{e}}$ and velocity dispersions are more robust. Our results clearly point to a "non-homology" in the total mass distribution of ETGs, which simulations of galaxy formation suggest may be related to a varying role of dissipation with galaxy mass.

15 pages, 6 figures, 3 tables, MNRAS in press

References in corpus (12)

• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• A systematic variation of the stellar initial mass function in early-type galaxies
• The Sloan Lens ACS Survey. V. The Full ACS Strong-Lens Sample
• The Structure & Dynamics of Massive Early-type Galaxies: On Homology, Isothermality and Isotropy inside one Effective Radius
• Towards a Concordant Model of Halo Occupation Statistics
• The X-Ray Concentration-Virial Mass Relation
• Separating baryons and dark matter in cluster cores: a full 2-D lensing and dynamic analysis of Abell 383 and MS2137-23
• The PN.S Elliptical Galaxy Survey: the dark matter in NGC 4494
• 2DPHOT: A Multi-purpose Environment for the Two-dimensional Analysis of Wide-field Images
• Unveiling dark halos in lensing galaxies
• The Optical Colors of Giant Elliptical Galaxies and their Metal-Rich Globular Clusters Indicate a Bottom-Heavy Initial Mass Function
• Dynamical and gravitational lensing properties of a new phenomenological model of elliptical galaxies

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