Two-dimensional kinematics of SLACS lenses – III. Mass structure and dynamics of early-type lens galaxies beyond z ≃ 0.1

By M. Barnabè, O. Czoske, Leon V. E. Koopmans, T. Treu, A. Stanford, K. Institute, U. Vienna, U. Barbara, U. Utah. 2011

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We combine in a self-consistent way the constraints from both gravitational lensing and stellar kinematics to perform a detailed investigation of the internal mass distribution, amount of dark matter, and dynamical structure of the 16 early-type lens galaxies from the Sloan Lens ACS Survey (SLACS Survey), at z= 0.08-0.33, for which both Hubble Space Telescope/Advanced camera for Surveys and NICMOS high-resolution imaging and Very Large Telescope VIMOS integral-field spectroscopy are available. Based on this data set, we analyse the inner regions of the galaxies, that is, typically within one (three-dimensional) effective radius re, under the assumption of axial symmetry and by constructing dynamical models supported by two-integral stellar distribution functions. For all systems, the total mass density distribution is found to be well approximated by a simple power law ? (with m being the ellipsoidal radius): this profile is on average slightly super-isothermal, with a logarithmic slope = 2.074+0.043-0.041 (errors indicate the 68 per cent confidence interval) and an intrinsic scatter ?, and is fairly round, with an average axial ratio = 0.77 ± 0.04. The lower limit for the dark matter fraction (fDM) inside re ranges, in individual systems, from nearly zero to almost a half, with a median value of 12 per cent. By including stellar masses derived from stellar population synthesis models with a Salpeter initial mass function (IMF), we obtain an average fDM= 31 per cent, and the corresponding stellar profiles are physically acceptable, with the exception of two cases where they only marginally exceed the total mass profile. fDM rises to 61 per cent if, instead, a Chabrier IMF is assumed. For both IMFs, the dark matter fraction increases with the total mass of the galaxy (correlation significant at the 3σ level). Based on the intrinsic angular momentum parameter calculated from our models, we find that the galaxies can be divided into two dynamically distinct groups, which are shown to correspond to the usual classes of the (observationally defined) slow and fast rotators. Overall, the SLACS systems are structurally and dynamically very similar to their nearby counterparts, indicating that the inner regions of early-type galaxies have undergone little, if any, evolution since redshift z≈ 0.35.

Subfields: Astronomy and Astrophysics, Instrumentation

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In Astronomy and Astrophysics

1. M. Cappellari
2. T. Treu
3. T. Naab
4. C. Conroy
5. P. Hopkins
6. L. Hernquist
7. Jeremiah P. Ostriker
8. A. Dekel

In Instrumentation

1. M. Cappellari
2. T. Treu
3. C. Conroy
4. T. Naab
5. P. Hopkins
6. Eric Emsellem
7. L. Hernquist
8. M. Sarzi

Citations in the corpus

• Dark halo response and the stellar initial mass function in early-type and late-type galaxies (2010, background): “Other c© 2011 RAS, MNRAS 000, 1–27 authors find similar mean values of γ (e.g., Dobke & King 2006; Auger et al. 2010; Barnabe et al. 2011).”
• SPIDER VIII - constraints on the stellar initial mass function of early-type galaxies from a variety of spectral features (2013, background): “…strong lensing studies of low-mass spheroids rejected a Salpeter IMF (Ferreras et al. 2005, 2008, 2010), recent work covering a wider range of galaxy mass hinted at systematic variations towards higher stellar M/L with increasing mass (Auger et al. 2010; Treu et al. 2010; Barnabé et al. 2011).”
• The stellar IMF in early-type galaxies from a non-degenerate set of optical line indices (2013, background): “E-mail: spiniello@astro.rug.nl ter (DM) fraction in the internal region of these systems increases with the mass of the galaxy (e.g. Zaritsky et al. 2006; Auger et al. 2010; Treu et al. 2010; Barnabè et al. 2011).”
• How do minor mergers promote inside-out growth of ellipticals, transforming the size, density profile and dark matter fraction? (2012, background): “…in the light of recent lensing observations, which predict an increasing dark matter fraction for more massive ellipticals (Auger et al. 2010; Barnabè et al. 2011), dynamical modeling (Gerhard et al. 2001; Cappellari 2012a) and the possibly low dark matter fractions in high redshift…”
• The ATLAS3D project – XX. Mass–size and mass–σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function (2012, methodology): “Barnabè et al. (2011) re-analysed 16 SLACS galaxies using axisymmetric, rather than spherical, dynamical models, and describing the galaxy images in detail, rather than assuming fixed Hernquist profiles.”
• 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 (2012, methodology): “Subsequent re-analyses of their data all confirmed a trend ρ tot(r) ∝ r−2.0, with an intrinsic scatter of ≈0.2 (Koopmans et al. 2006, 2009; Auger et al. 2010b; Barnabè et al. 2011).”
• Inference of the cold dark matter substructure mass function at z = 0.2 using strong gravitational lenses (2014, methodology): “…under the assumption of a singular isothermal elliptical (SIE) mass distribution, were derived by Bolton et al. (2008) (see also Auger et al. 2009), while for a subset of the lenses considered here, a joint lensing and 2D kinematics analysis can be found in the paper by Barnabè et al. (2011).”
• Mass-sheet degeneracy, power-law models and external convergence: Impact on the determination of the Hubble constant from gravitational lensing (2013, methodology): “This technique has been applied to several lensing galaxies from the SLACS sample (e.g. Barnabé et al. 2009, 2011).”
• THE POPULATION OF GALAXY–GALAXY STRONG LENSES IN FORTHCOMING OPTICAL IMAGING SURVEYS (2015, methodology): “The sample has been used to constrain the masses and density profiles of galaxies (Auger et al. 2010; Barnabè et al. 2011), the dark sub-halo population (Vegetti et al. 2014), cosmological parameters (Collett & Auger 2014; Oguri et al. 2012; Suyu et al. 2014), the high redshift luminosity function…”
• AGN-driven quenching of star formation: morphological and dynamical implications for early-type galaxies (2013, background): “The slope of the total mass density profile measured by strong lensing provides a value close to isothermal γ = −2.078 (ρ tot ∝ rγ ) at z = 0.2 for ETGs (Koopmans et al. 2009; Auger et al. 2010; Barnabè et al. 2011).”
• H0LiCOW - IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology (2016, background): “Past studies have shown that a powerlaw model provides an good general description of typical lens galaxies at the length scales we are interested in (e.g., Koopmans et al. 2006, 2009; Suyu et al. 2009; Auger et al. 2010; Barnabè et al. 2011; Sonnenfeld et al. 2013).”
• CMU DeepLens: deep learning for automatic image-based galaxy–galaxy strong lens finding (2017, methodology): “For example, moderate-sized samples of galaxy-scale strong lenses from the Sloan Lens ACS (SLACS) survey (Bolton et al. 2006) have been used to derive ensemble constraints on the total matter profile in massive elliptical galaxies (e.g. Koopmans et al. 2006; Auger et al. 2010; Barnabè et al. 2011).”
• TDCOSMO IV: Hierarchical time-delay cosmography -- joint inference of the Hubble constant and galaxy density profiles (2020, methodology): “The VLT VIMOS IFU data set is described in Czoske et al. (2008) and subsequently used in Barnabè et al. (2009, 2011), Czoske et al. (2012).”
• TDCOSMO. I. An exploration of systematic uncertainties in the inference of $H_0$ from time-delay cosmography (2019, background): “…dispersion integrated within an aperture, σv, has been used even though additional and substantial gains can be obtained by including spatially resolved information that helps break the mass-anisotropy degeneracy (Barnabè et al. 2011; Czoske et al. 2012; Shajib et al. 2018; Yıldırım et al. 2020).”
• Galaxy Masses: A Review (2013, methodology): “Based on a subset of 16 lens ETGs with deep integral field spectroscopy Barnabè et al. (2011) find 〈γ′〉 >= 2.074+0.043−0.041 with an intrinsic scatter of 0.143 +0.054 −0.014.”
• H0LiCOW – I. H0 Lenses in COSMOGRAIL's wellspring: program overview (2016, background): “…in the lens galaxies by combining lensing and kinematics data, and also infer the stellar mass of the lens galaxies (e.g., Treu & Koopmans 2004; Barnabè et al. 2011; 10 with spectroscopic observations of HE 1104−1805 pending for lens velocity dispersion measurement MNRAS 000, 1–16…”