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

MNRAS 432, 1709–1741 (2013) doi:10.1093/mnras/stt562 Advance Access publication 2013 May 11 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 Michele Cappellari,1‹ Nicholas Scott,1,2 Katherine Alatalo,3 Leo Blitz,3 Maxime Bois,4 Frédéric Bournaud,5 M. Bureau,1 Alison F. Crocker,6 Roger L. Davies,1 Timothy A. Davis,1,7 P. T. de Zeeuw,7,8 Pierre-Alain Duc,5 Eric Emsellem,7,9 Sadegh Khochfar,10 Davor Krajnović,7 Harald Kuntschner,7 Richard M. McDermid,11 Raffaella Morganti,12,13 Thorsten Naab,14 Tom Oosterloo,12,13 Marc Sarzi,15 Paolo Serra,12 Anne-Marie Weijmans16 and Lisa M. Young17 2 Centre for Astrophysics & Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia 3 Department of Astronomy, Campbell Hall, University of California, Berkeley, CA 94720, USA 4 Observatoire de Paris, LERMA and CNRS, 61 Av. de l’Observatoire, F-75014 Paris, France 5 Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp CNRS Université Paris Diderot, F-91191 Gif-sur-Yvette Cedex, France 6 Department of Astrophysics, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, USA 7 European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany 8 Sterrewacht Leiden, Leiden University, Postbus 9513, NL-2300 RA Leiden, the Netherlands 9 Université Lyon 1, Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon and Ecole Normale Supérieure de Lyon, 9 avenue Charles André, F-69230 Saint-Genis Laval, France 10 Max-Planck Institut für extraterrestrische Physik, PO Box 1312, D-85478 Garching, Germany 11 Gemini Observatory, Northern Operations Centre, 670 N. A‘ohoku Place, Hilo, HI 96720, USA 12 Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, NL-7990 AA Dwingeloo, the Netherlands 13 Kapteyn Astronomical Institute, University of Groningen, Postbus 800, NL-9700 AV Groningen, the Netherlands 14 Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching, Germany 15 Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL1 9AB, UK 16 Dunlap Institute for Astronomy & Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M5S 3H4, Canada 17 Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA Accepted 2013 March 27. Received 2013 March 12; in original form 2012 August 16 ABSTRACT We study the volume-limited and nearly mass-selected (stellar mass Mstars  6 × 109 M ) ATLAS3D sample of 260 early-type galaxies (ETGs, ellipticals Es and lenticulars S0s). We construct detailed axisymmetric dynamical models (Jeans Anisotropic MGE), 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 mass-to-light ratios (M/L)e and dark matter fractions fDM , within a sphere of radius r = Re centred on the galaxies. We also measure the stellar (M/L)stars and derive a median dark matter fraction fDM = 13 per cent in our sample. We infer masses MJAM ≡ L × (M/L)e ≈ 2 × M1/2 , where M1/2 is the total mass within a sphere enclosing half of the galaxy light. We find that the thin two-dimensional subset spanned by galaxies in the maj (MJAM , σe , Re ) coordinates system, which we call the Mass Plane (MP) has an observed maj rms scatter of 19 per cent, which implies an intrinsic one of 11 per cent. Here, Re is the major axis of an isophote enclosing half of the observed galaxy light, while σ e is measured  E-mail:  C 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society 1 Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK 1710 M. Cappellari et al. maj Key words: galaxies: elliptical and lenticular, cD – galaxies: evolution – galaxies: formation – galaxies: kinematics and dynamics – galaxies: structure. 1 I N T RO D U C T I O N Scaling relations of early-type galaxies (ETGs, ellipticals Es and lenticulars S0s) have played a central role in our understanding of galaxy evolution, since the discovery that the stellar velocity dispersion σ (Minkowski 1962; Faber & Jackson 1976) and the galaxy projected half-light radius Re (Kormendy 1977) correlate with galaxy luminosity L. An important step forward was made with the discovery that these two relations are just projections of a relatively narrow plane, the Fundamental Plane (FP) (Djorgovski & Davis 1987; Dressler et al. 1987; Faber et al. 1987), relating the three variables (L, σe , Re ). When the plane is used as a distance indicator, as was especially the case at the time of its discovery, the luminosity can be replaced by the surface brightness within Re as e ≡ L/(2πRe2 ) and the observed plane assumes the form Re ∝ σ 1.33 e−0.82 , (1) where the adopted parameters are the median of the 11 independent determinations tabulated in Bernardi et al. (2003). It was immediately realized that the existence of the FP could be due to the galaxies being in virial equilibrium (e.g. Binney & Tremaine 2008) and that the deviation (tilt) of the coefficients from the virial predictions Re ∝ σ 2 e−1 , could be explained by a smooth power-law variation of mass-to-light ratio (M/L) with mass (Faber et al. 1987). The FP showed that galaxies assemble via regular processes and that their properties are closely related to their mass. The tightness of the plane gives constraints on the variation of stellar population among galaxies of similar characteristics and on their dark matter content (Renzini & Ciotti 1993; Borriello, Salucci & Danese 2003). The regularity also allows one to use the FP to study galaxy evolution, by tracing its variations with redshift (van Dokkum & Franx 1996). However, other reasons for the deviation of the coefficients are possible: the constant coefficients in the simple virial relation only rigorously apply if galaxies are spherical and homologous systems, with similar profiles and dark matter fraction. But both galaxies concentration (Caon, Capaccioli & D’Onofrio 1993) and the amount of random motions in their stars (Davies et al. 1983) were found to systematically increase with galaxy luminosity. The uncertain origin of the tilt led to a large number of investigations about its origin, exploring the effects of (i) the systematic variation in the stellar population or initial mass function (IMF; e.g. Prugniel & Simien 1996; Forbes, Ponman & Brown 1998) or (ii) the non-homology in the surface brightness distribution (e.g. Graham & Colless 1997; Prugniel & Simien 1997; Bertin, Ciotti & Del Principe 2002; Trujillo, Burkert & Bell 2004) or (iii) the kinematics (e.g. Prugniel & Simien 1994; Busarello et al. 1997) or (iv) the variation in the amount (...truncated)