The Atlas3D project - XV. Benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, Fundamental Plane and Mass Plane

摘要

We study the volume-limited and nearly mass selected (stellar mass M>6*10^9Msun) Atlas3D sample of 260 early-type galaxies. We construct detailedaxisymmetric dynamical models (JAM), which allow for orbital anisotropy,include a dark matter halo, and reproduce in detail both the galaxy images andthe high-quality integral-field stellar kinematics. We derive accurate totalM/L and dark matter fractions f_DM, within a sphere of radius r=Re. We alsomeasure the stellar M/L and derive a median dark matter fraction f_DM=13%. Wefind that the thin two-dimensional subset spanned by galaxies in the(M_JAM,sigma_e,R_e) coordinates system, which we call the Mass Plane (MP) hasan observed rms scatter of 19% and an intrinsic one of 11%. The MP satisfiesthe scalar virial relation M_JAM sigma_e^2 R_e within our tight errors.However, the details of how both Re and sigma_e are determined are critical indefining the precise deviation from the virial exponents. We revisit the(M/L)-sigma_e relation, which describes most of the deviations between the MPand the FP. The best-fitting relation is (M/L) sigma_e^0.72 (r-band). Itprovides an upper limit to any systematic increase of the IMF massnormalization with sigma_e. We study of the link between sigma_e and thegalaxies circular velocity V_circ within 1Re (where stars dominate) and findthe relation max(V_circ)~1.76*sigma_e, which has an observed scatter of 7%. Theaccurate parameters described in this paper are used in the companion Paper XXof this series to explore the variation of global galaxy properties, includingthe IMF, on the projections of the MP. [Abridged]