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THE STRUCTURE AND DYNAMICS OF MASSIVE EARLY-TYPE GALAXIES: ON HOMOLOGY, ISOTHERMALITY, AND ISOTROPY INSIDE ONE EFFECTIVE RADIUS

L. V. E. KoopmansKapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV Groningen, The NetherlandsA. BoltonInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822, USA; [email protected]Tommaso TreuDepartment of Physics, University of California, Santa Barbara, CA 93106, USA; [email protected]O. CzoskeKapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV Groningen, The NetherlandsMatthew W. AugerDepartment of Physics, University of California, Santa Barbara, CA 93106, USA; [email protected]Matteo BarnabèKapteyn Astronomical Institute, University of Groningen, P.O.Box 800, 9700 AV Groningen, The Netherlands; [email protected]S. VegettiKapteyn Astronomical Institute, Univ. of Groningen, P.O. Box 800, 9700 AV Groningen, The NetherlandsR. GavazziInstitut d'Astrophysique de Paris, UMR7095 CNRS - Université Paris 6, 98bis Bd Arago, 75014 Paris, FranceLeonidas A. MoustakasJPL/Caltech, MS 169-327, 4800 Oak Grove Dr., Pasadena, CA 91109, USAScott BurlesDepartment of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; [email protected]

2009en

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ABI

Annotatsiya

Based on 58 SLACS strong-lens early-type galaxies (ETGs) with direct total-mass and stellar-velocity dispersion measurements, we find that inside one effective radius massive elliptical galaxies with M eff 3 10 10 M are well approximated by a power-law ellipsoid, with an average logarithmic density slope of LD -d log( tot )/d log(r) = 2.085 +0.025 -0.018 (random error on mean) for isotropic orbits with r = 0, 0.1 (syst.) and 0.20 +0.04 -0.02 intrinsic scatter (all errors indicate the 68% CL). We find no correlation of LD with galaxy mass (M eff ), rescaled radius (i.e., R einst /R eff ) or redshift, despite intrinsic differences in density-slope between galaxies. Based on scaling relations, the average logarithmic density slope can be derived in an alternative manner, fully independent from dynamics, yielding SR = 1.959 0.077. Agreement between the two values is reached for r = 0.45 0.25, consistent with mild radial anisotropy. This agreement supports the robustness of our results, despite the increase in mass-to-light ratio with total galaxy mass:

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DOI: 10.1088/0004-637x/703/1/l51

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