Integral-Field Spectroscopy of SLACS Lenses. Oliver Czoske Kapteyn Institute, Groningen, NL

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1 Integral-Field Spectroscopy of SLACS Lenses Oliver Czoske Kapteyn Institute, Groningen, NL Three decades of gravitational lenses Symposium at the JENAM, April 2009 Hatfield, 23 April 2009

2 Collaborators Léon Koopmans (Kapteyn) Matteo Barnabè (Kapteyn) Tommaso Treu (UCSB) Matt Auger (UCSB) Adam Bolton (IfA, Hawai i) Scott Trager (Kapteyn)

3 Introduction Dynamical studies of early-type galaxies have a long history (R. Minkowski, 1950s) One of the latest efforts: SAURON 48 local (!) elliptical and lenticular galaxies SAURON IFS on WHT cz < 3000 km s 1 Detailed dynamical modelling But: require fairly strong assumptions, e.g. constant M/L see also ATLAS 3D Goal of our project: extend structural studies of early-type galaxies beyond the local universe Emsellem et al. (2004) 3

4 Gravitational Lensing Advantages of gravitational lensing: robust and model-independent estimate of total mass contained within Einstein ring sensitive to all kinds of matter (DM + stars + gas +... ) insensitive to dynamic state of matter But: model degeneracies! These can be broken by combination with, e.g., kinematic information. Lenses Structures and Dynamics (L. Koopmans, T. Treu) detection of DM halos at high significance inner total mass profiles close to isothermal etc... (MG2016, Léon Koopmans) 4

5 Sloan Lens ACS Survey SLACS is a lens selected gravitational lens survey: candidates are chosen from the SDSS luminous red galaxy sample + quiescent MAIN sample selection criterion: presence of additional emission lines at higher redshift Bolton et al follow-up observations with ACS or WFPC2: confirmation of lensing hypothesis lenses are guaranteed to be bright and not outshone by the lensed background objects SLACS lenses are normal early-type galaxies Treu et al SLACS is the ideal parent sample for a combined lensing/dynamical analysis

6 Sloan Lens ACS Survey SLACS is a lens selected gravitational lens survey: candidates are chosen from the SDSS luminous red galaxy sample + quiescent MAIN sample selection criterion: presence of additional emission lines at higher redshift Bolton et al follow-up observations with ACS or WFPC2: confirmation of lensing hypothesis lenses are guaranteed to be bright and not outshone by the lensed background objects SLACS lenses are normal early-type galaxies Treu et al SLACS is the ideal parent sample for a combined lensing/dynamical analysis 5

7 Project Goals of this project: obtain two-dimensional maps of galaxy kinematics, i.e. v(r) and σ los (R) using 1. VIMOS/IFU on VLT: 17 systems (Czoske) 2. pseudo integral field spectra from Keck: 13 systems (Treu, Gavazzi, Auger) Combine lens modelling with detailed modelling of the kinematical information in a fully self-consistent way (Barnabè) Velocity Dispersion (km/s) SAURON E/S0 (Cappellari et al. 2007) Redshift 6

8 Project Observations: ESO/Large programme with VIMOS/IFU Spectral resolution: R 2500 v km s 1 Fibre size: 0.67 arcsec kpc Data reduction: VIPGI Kinematic analysis: Template fitting in pixel space v(x, y), σ(x, y) J z lens = z source = σ v = 275 ± 12 J z lens = z source = σ v = 332 ± 23 J z lens = z source = σ v = 283 ± 18 J z lens = z source = σ v = 260 ± 15 7

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12 CAULDRON Combined Algorithm for Unified Lensing and Dynamics ReconstructiON Axisymmetric density distribution: ρ(r, z) Gravitational potential: Φ(R, z, η k ) linear optimization Lensed image reconstruction Ls + n L = d Dynamical model Qγ + n D = p linear optimization Maximize the Bayesian evidence allows model comparison automatically embodies Occam s razor non-linear optimization: vary η k at convergence Best values for the non-linear parameters η k source reconstruction & DF reconstruction Barnabè & Koopmans (2007) 10

13 CAULDRON Dynamical model: axisymmetric density distribution, ρ m γ two-integral model, i.e. orbits conserve E and L z reconstruction with Schwarzschild-type method, components (TICs) using two-integral result of reconstruction: weights for TIC(E, L z ) stellar distribution function in the form of So far analyzed six systems in detail (Czoske et al., 2008; Barnabè et al., 2009). 11

14 J : Results Lensing Dynamics adopted model: Power Law inclination: i = 67.8 ± 0.01 ρ(r, z) (R 2 + z 2 /q 2 ) γ/2 slope: γ = 2.08 ± 0.01 axis ratio: q = ± 0.01 lens strength: α 0 = ±

15 J : Results Lensing Dynamics adopted model: Power Law inclination: i = 67.5 ± 0.1 ρ(r, z) (R 2 + z 2 /q 2 ) γ/2 slope: γ = 1.97 ± 0.01 axis ratio: q = 0.81 ± 0.1 lens strength: α 0 = ±

16 J : Results Lensing Dynamics adopted model: Power Law inclination: i = 82.4 ± 0.01 ρ(r, z) (R 2 + z 2 /q 2 ) γ/2 slope: γ = ± axis ratio: q = ± lens strength: α 0 = ±

17 Mass profiles Dark matter fraction Einstein radius kinem. data extent effective radius Maximum bulge hypothesis = lower limit for DM fraction DM fraction % at r eff /2 and % at r eff stellar mass-to-light ratio 5 < (M/L) B < 9 Barnabè et al. (2009) 15

18 Total mass profiles logarithmic slope axisymmetric power-law density profile ρ m γ generally fits the data well logarithmic slope γ = 1.98 ± 0.05 = isothermal bulge-halo conspiracy no apparent evolution with redshift (also including higher-z LSD systems of Koopmans & Treu) Barnabè et al. (2009) 16

19 Summary self-consistent combined analysis of lensing and 2D kinematics of earlytype galaxies application to 17 lens systems from SLACS is starting to give serious results in-depth analysis of 6 systems: axisymmetric, power-law profile, two-integral models fit well density slope γ = 1.98 ± 0.05 dark-matter fraction > % at effective radius Outlook: analysis of full sample stellar population analysis (w/scott Trager) add in 13 systems observed with Keck for a total of 30 lens systems 17

20 Contents 1 2 Collaborators 3 SLACS IFS Introduction 4 SLACS IFS Gravitational Lensing 5 SLACS IFS Sloan Lens ACS Survey 6 SLACS IFS Project 7 SLACS IFS Project SLACS IFS CAULDRON 11 SLACS IFS CAULDRON 12 Combined analysis: SDSS J2321 (z = ) 13 SLACS IFS J : Results 14 SLACS IFS J : Results 15 SLACS IFS J : Results 16 Mass profiles Dark matter fraction 17 Total mass profiles logarithmic slope 18 Summary 19 Contents 18