The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the Fundamental Plane of elliptical and lenticular galaxies

By M. Cappellari, R. Bacon, M. Bureau, M. Damen, Roger Davies, P. de Zeeuw, Eric Emsellem, J. Falc'on-Barroso, D. Krajnovi'c, H. Kuntschner and 5 more. 2005

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We investigate the well-known correlations between the dynamical mass-to-light ratio M/L and other global observables of elliptical (E) and lenticul ar (S0) galaxies. We construct twointegral Jeans and three-integral Schwarzschild dynamical models for a sample of 25 E/S0 galaxies with SAURON integral-field stellar kinematics to about one effective (h alf-light) radius Re. They have well-calibrated I-band Hubble Space TelescopeWFPC2 and large-field ground-based photometry, accurate surface brightness fluc tuation distances, and their observed kinematics is consistent with an axisymmetric intrinsic sh ape. All these factors result in an unprecedented accuracy in the M/L measurements. We find a tight correlation of the form (M/L) = (3.80 ± 0.14) × (σe/200 km s 1 ) 0.84±0.07 between the M/L (in the I-band) measured from the dynamical models and the luminosity-weighted second moment σe of the lineof-sight velocity-distribution within Re. The observed rms scatter in M/L for our sample is 18%, while the inferred intrinsic scatter is � 13%. The (M/L)‐σe relation can be included in the remarkable series of tight correlations between σe and other galaxy global observables. The comparison of the observed correlations with the predictions of the Fundamental Plane (FP), and with simple virial estimates, shows that the ‘tilt ’ of the FP of early-type galaxies, describing the deviation of the FP from the virial relation, is almost exclusively due to a real M/L variation, while structural and orbital non-homology have a negligible effect. When the photometric parameters are determined in the ‘classic’ way , using growth curves, and the σe is measured in a large aperture, the virial mass appears to be a reliable estimator of the mass in the central regions of galaxies, and can be safely used where more ‘expensive’ models are not feasible (e.g. in high redshift studies). In this case th e best-fitting virial relation has the form (M/L)vir = (5.0±0.1)×Reσ 2 e/(L G), in reasonable agreement with simple theoretical predictions. We find no difference between the M/L of the galaxies in clusters and in the field. The comparison of the dynamical M/L with the (M/L)pop inferred from the analysis of the stellar population, indicates a median dark matter fractio n in early-type galaxies of � 30% of the total mass inside one Re, in broad agreement with previous studies, and it also shows that the stellar initial mass function varies little among d ifferent galaxies. Our results suggest a variation in M/L at constant (M/L)pop, which seems to be linked to the galaxy dynamics. We speculate that fast rotating galaxies have lower dark matte r fractions than the slow rotating and generally more massive ones. If correct, this would suggest a connection between the galaxy assembly history and the dark matter halo structure. The tightness of our correlation provides some evidence against cuspy nuclear dark matter profiles in g alaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a1f080049320331f4fd537add5d61576897288f7

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Citations in the corpus

ON SIZES, KINEMATICS, M/L GRADIENTS, AND LIGHT PROFILES OF MASSIVE COMPACT GALAXIES AT z ∼ 2 (2010, background): “The dashed line indicates the proportionality followed by present-day early-type galaxies (van Dokkum & Stanford 2003; Cappellari et al. 2006).”
THE MBH–LSPHEROID RELATION AT HIGH AND LOW MASSES, THE QUADRATIC GROWTH OF BLACK HOLES, AND INTERMEDIATE-MASS BLACK HOLE CANDIDATES (2012, methodology): “If (M/L)dynamical ∝ L1/3 then one expects Mbh ∝ L8/3.”
THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES (2012, background): “This is because the unknown IMF is the dominant source of uncertainty in the absolute mass scale for stellar population synthesis models, especially for old galaxies (e.g., Bell & de Jong 2001; Bundy et al. 2005; Cappellari et al. 2006; Auger et al. 2009; Grillo et al. 2009; Stott et al. 2010).”
The SAURON project – IX. A kinematic classification for early‐type galaxies (2007, background): “The existence of these two classes must be linked to the formation and evolution of early-type galaxies, and is in any case a key to understand their dynamical state (see also Cappellari et al. 2006, hereaft r Paper IV).”
Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365 (2007, methodology): “6 in Cappellari et al. 2006).”
VLT/VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies: 2D kinematic properties (2013, neutral): “We have considered a mean value ofK = 6, which is also close to the one found by other authors11 (e.g., Cappellari et al. 2006).”
GALAXY CLUSTER BARYON FRACTIONS REVISITED (2013, methodology): “Equation (9) in Cappellari et al. (2006) quantifies the luminosity dependence of ϒ in the I-band, which is consistent with more recent observations from ATLAS3D (M. Cappellari 2012, private communication).”
Red mergers and the assembly of massive elliptical galaxies: the fundamental plane and its projections (2006, background): “A number of authors have argued that stellar population variations with galaxy mass are responsible for the fundamental plane tilt (e.g. Gerhard et al. 2001; Treu et al. 2005; Cappellari et al. 2006).”
A Fundamental Relation between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies (2006, methodology): “Here G is the gravitational constant and α = 5 (Cappellari et al. 2006); the geometric effective radius, Re = a √ 1 − ǫ, a being the radius measured along the isophotal semi-major axis, is taken from Ferrarese et al. (2006) for the ACSVCS galaxies, and from Marconi & Hunt (2003) for the galaxies…”
GALAXY ZOO: THE FUNDAMENTALLY DIFFERENT CO-EVOLUTION OF SUPERMASSIVE BLACK HOLES AND THEIR EARLY- AND LATE-TYPE HOST GALAXIES (2010, methodology): “Since the fixed SDSS spectroscopic fibre samples the light out to a different fraction of the effective radius, we use the empirical correction derived by Cappellari et al. (2006) to correct the velocity dispersion to the effective radius of the bulge surface-brightness profile.”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, background): “…galaxies, a variety of galaxy-weighing methods exist which rely on either the availability of kinematic tracers (e.g. Wilkinson & Evans 1999; Cappellari et al. 2006; Xue et al. 2008) or the presence of a gravitational lensing signal (e.g. Kochanek, Keeton & McLeod 2001), or both (e.g. Sand,…”
From star clusters to dwarf galaxies: the properties of dynamically hot stellar systems (2008, background): “Also 4 Cappellari et al. (2006) do not discuss gas as a possible contributor to the non-luminous matter.”
Environment and self-regulation in galaxy formation (2009, methodology): “Masses are derived from velocity dispersion and effective radius through the scaling provided by Cappellari et al. (2006).”
COUNTING LOW-MASS STARS IN INTEGRATED LIGHT (2011, background): “This would imply a mass-to-light ratio ofM/L ≈ 40, which we know now is strongly ruled out on dynamical grounds (e.g., Cappellari et al. 2006).”
Ages and metallicities of early-type galaxies in the SDSS: new insight into the physical origin of the colour-magnitude and the Mg2-sigmaV relations (2006, methodology): “As a check, we tried steeper velocity dispersion profiles, with slopes −0.06 (Mehlert et al. 2003) and −0.066 (Cappellari et al. 2006).”