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The Atlas3D project - XIX. Benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, Fundamental Plane and Virial Plane | | Michele Cappellari
; Nicholas Scott
; Katherine Alatalo
; Leo Blitz
; Maxime Bois
; Frederic Bournaud
; M. Bureau
; Alison F. Crocker
; Roger L. Davies
; Timothy A. Davis
; P. T. de Zeeuw
; Pierre-Alain Duc
; Sadegh Khochfar
; Davor Krajnovic
; Harald Kuntschner
; Richard M. McDermid
; Raffaella Morganti
; Thorsten Naab
; Tom Oosterloo
; Marc Sarzi
; Paolo Serra
; Anne-Marie Weijmans
; Lisa M. Young
; | | Date: |
17 Aug 2012 | | Abstract: | We study the volume-limited Atlas3D sample of 260 early-type galaxies. We
construct detailed axisymmetric dynamical models, which allow for orbital
anisotropy, include a dark matter halo, and reproduce in detail both the galaxy
images and the high-quality integral-field stellar kinematics out to about 1Re,
the projected half-light radius. We derive accurate total (M/L)_e and dark
matter fractions f_DM, within a sphere of radius r=Re. We infer masses M_JAM
and stellar (M/L)_stars. We find that the thin two-dimensional subset spanned
by galaxies in the (M_JAM,sigma_e,R_e^max) coordinates system, which we call
the Virial Plane (VP) has an observed rms scatter of 17%, which would imply an
intrinsic one of just 4%. The VP satisfies the scalar virial relation
M_JAM=5.0*sigma_e^2 R_e^max/G within our tight errors. However, the details of
how both Re and sigma_e are determined are critical in defining the precise
deviation from this simple virial form. We measure a median dark matter
fractions of f_DM=16% in our sample, which implies the total density profile
within 1Re is dominated by the stellar density. When approximated by a
power-law the latter has the ’isotermal’ form rho_stars ~ r^-2.0 with an
intrinsic rms scatter of 0.2. The (M/L)_e-sigma_e relation, which describes
most of the deviations between the VP and the FP is (M/L)_e ~ sigma_e^0.69.
This relation provides an upper limit to any increase of the IMF mass
normalization with sigma_e. We study the relations between sigma_e and the
galaxies circular velocity within 1Re and find the two empirical relations
V_c(R_e^max) ~ 1.51*sigma_e and max(V_circ) ~ 1.76*sigma_e. [Abridged] | | Source: | arXiv, 1208.3522 | | Services: | Forum | Review | PDF | Favorites | |
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