SLACS Spectroscopy. Observations, Kinematics & Stellar Populations. Oliver Czoske Kapteyn Institute, Groningen, NL

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1 SLACS Spectroscopy Observations, Kinematics & Stellar Populations Oliver Czoske Kapteyn Institute, Groningen, NL Strong Gravitational Lensing in the Next Decade Cogne, 22 June 2009

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

3 Spectra of early-type galaxies Galaxy spectrum s(λ): sum of (many) Doppler shifted stellar spectra t(λ) ( s(λ) G(v) t ln λ v ) dv c G(v): line-of-sight velocity distribution (LOSVD) Moments: v = G(v) v dv σ 2 = G(v)(v v) 2 dv value 3.0e e e 16 value Galaxy (J2238), σ = 200km/s lambda Star (HD ), Indo US lambda = galaxy spectra contain information on stellar kinematics 3

A little history Minkowski (1950s) the telescope as analogue computer Burbidge 2 & Fish (1961) numerical convolution Brault & White (1971), Simkin (1974) introduction of FFT into astronomy Sargent et

4 A little history Minkowski (1950s) the telescope as analogue computer Burbidge 2 & Fish (1961) numerical convolution Brault & White (1971), Simkin (1974) introduction of FFT into astronomy Sargent et al. (1977) (Paul Schechter) Fourier quotient method: G s/ t Tonry & Davis (1979) cross-correlation method Franx et al. (1989) fitting in Fourier space Rix & White (1992), van der Marel & Franx (1993), Cappellari & Emsellem (2004) fitting in pixel space Rudolf Minkowski ( ) 4

5 a 3 Spatially resolved kinematics N E PA a 1 Longslit spectroscopy: major and minor axis profiles of v and σ = at least some ellipticals rotate Tensor virial theorem: 2K + W = 2(T Π) + W = 0 v σ = 2(1 δ) ( Wxx W zz ) (ε) 2 Roberts (1962), Binney (1978) W xx /W zz : ratio of components of potential energy tensor δ = Π zz /Π xx : anisotropy of random kinematic energy tensor 5

6 Spatially resolved kinematics δ = 0 M B < 20.5 M B < 20.5 bulges δ > 0 Illingworth & Schechter 1981 Davies et al. (1983) massive galaxies are supported by anisotropic pressure less massive galaxies and bulges are supported by rotation occasional minor axis rotation: kinematical hint at triaxiality 6

7 Integral-field spectroscopy y λ λ x λ lenslets + fibres image slicer... = Three-dimensional data cubes (x, y, f (λ)) = Two-dimensional maps of v(x, y), σ(x, y),... line strength, metallicities, star formation rate,... 7

8 State of the art: 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) 8

9 SLACS IFS 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) 9

10 SLACS IFS 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

2006 follow-up observations with ACS or WFPC2: confirmation of lensing hypothesis lenses are guaranteed to be bright and not outshone by the

11 SLACS IFS 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 10

12 SLACS IFS 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 11

The Integral Field Unit of VIMOS on VLT Quadrant 2 (to

(to Mask 1) C B 1 2 3 4 5 A D 20 21 1 40 60 41 61 80 1 2 3

13 The Integral Field Unit of VIMOS on VLT Quadrant 2 (to Mask 2) D A B C Quadrant 1 (to Mask 1) C B A D (b) A B C D Quadrant 3 (to Mask 3) (a) Quadrant 4 (to Mask 4) Mask 3 (c) Zanichelli et al. (2005) Photos from 12

14 SLACS IFS 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 13

15 14

17 15

18 Integrated spectra (SDSS aperture, 3 arcsec) SDSS J0037 'HD 249 ' sigma = gof = 7.49 SDSS J1251 'HD ' sigma = gof = 4.38 Rel. Flux Residuals Rel. Flux 1.6e e 16 1e 16 0e+00 1e 16 3e 16 5e Wavelength Residuals Wavelength SDSS J1451 'HD ' sigma = gof = Wavelength Residuals Rel. Flux Residuals Rel. Flux 6.0e e 16 2e 17 2e e e Wavelength Residuals Wavelength SDSS J1627 'HD ' sigma = gof = Wavelength Residuals direct pixel-fitting method template chosen from IndoUS database ( 1000 spectra covering wide range of stellar parameters) single stellar template for each system, chosen from global spectrum, used for each spaxel additive and multiplicative polynomials to correct for continuum and sensitivity variations emission lines, Balmer lines, Mg b masked, as well as sky line residuals Residuals 4e 17 0e+00 3e Residuals 2e 17 1e 17 4e Wavelength Wavelength 16

19 Integrated spectra (SDSS aperture, 3 arcsec) Even when the fit doesn t look so good: source features 17

20 Integrated spectra: Stellar population analysis Oops nothing there yet... 18

21 Integrated spectra: Stellar population analysis stellar population analysis to yield stellar M/L and stellar age combined lensing/dynamics model yields total mass distribution and stellar distribution function, but requires assumption stellar M/L combine with surface brightness and stellar M/L: distribution of dark matter How do the structural histories/properties of the galaxies compare to their star formation histories? Stellar population studies will be more robust with larger wavelength coverage than VIMOS. 19

22 Results: Angular momentum parameter λ R M B SAURON SLACS/IFU λ R = i F i R i v i i F i R i v 2 i + σ2 i Emsellem et al. (2007) fast rotators vs slow rotators, λ R 0.1 fast rotators tend to have low luminosity, M B 20.5 SLACS/IFU sample mostly slow rotators, consequence of selection of high velocity dispersion systems 20

23 Results: v/σ ε diagram Binney (2005): Updated version of v/σ ε diagram, appropriate for two- (or three?)-dimensional data: ṽ 2 σ 2 := i F i v 2 i i F i σ 2 i From tensor virial theorem derive ṽ 2 σ 2 = (1 δ)w xx/w zz 1 α(1 δ)w xx /W zz + 1 with α = 1 M ṽ 2 d 3 x [ v (x) ṽ (x ) ] 2 ρ(x) For Hernquist profile with flat rotation curve: α

24 Results: v/σ ε diagram v σ δ = 0 α = 0 α = 0.2 δ = 0.5 δ SAURON SLACS/IFU ε σ v 2 σ = (1 δ)w xx/w zz 1 2 α(1 δ)w xx /W zz + 1 δ = 1 Π zz Π xx 22

Velocity Dispersion (km/s) 0 100 200 300 400 SAURON E/S0 (Cappellari et al. 2007) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.

25 Future directions extend redshift coverage to z 1 with samples of adequate size extend mass coverage to σ < 200 km s 1 better resolution: resolve central peak in velocity dispersion broad wavelength coverage for stellar population studies Velocity Dispersion (km/s) SAURON E/S0 (Cappellari et al. 2007) Redshift Future lens surveys will provide ample material to choose from for in-depth studies of galaxy properties. 23

26 Next generation instruments and telescopes: XShooter on VLT large wavelength coverage: ,000 Å (three arms) spectral resolution: R 5100 (twice that of VIMOS) small field of view: arcsec 2 = GTO project to observe three massive lens galaxies at z 1 (PI: Koopmans) 24

27 Next generation instruments and telescopes: Parameterss Resolution Field of view 25

28 Next generation instruments and telescopes: ELT et al. Telescopes of 30 m and more will be a reality within 10 years or so Spectroscopy will continue to be one of the main jobs of ground-based telescopes Integral-field spectrographs are complex, but provide high information density in their data Do lensing studies (not just of galaxies, but also of lensed sources, also in cluster lenses) have specific requirements for instrument design that we should try to push? ESO-ELT: 42 m primary, fully adaptive 26

29 Conclusions Current IFS instrumentation gives useful data to begin studying galaxy kinematics beyond the local universe. VIMOS/IFU data on a subsample of SLACS lenses show that these form a continuation of the local SAURON sample = massive, mostly slowly rotating galaxies full power of these data unleashed when combined with lensing information = Matteo s talk future instrumentation should improve coverage of galaxy parameters (redshift, mass), as well as improve the accuracy of kinematic studies 27

30 Contents 1 2 Collaborators 3 Spectra of early-type galaxies 4 A little history 5 Spatially resolved kinematics 6 Spatially resolved kinematics 7 Integral-field spectroscopy 8 State of the art: SAURON 9 SLACS IFS Gravitational Lensing 10 SLACS IFS Sloan Lens ACS Survey 11 SLACS IFS Project 12 The Integral Field Unit of VIMOS on VLT 13 SLACS IFS Project Integrated spectra (SDSS aperture, 3 arcsec) 17 Integrated spectra (SDSS aperture, 3 arcsec) 18 Integrated spectra: Stellar population analysis 19 Integrated spectra: Stellar population analysis 20 Results: Angular momentum parameter 21 Results: v/σ ε diagram 22 Results: v/σ ε diagram 23 Future directions 28

31 24 Next generation instruments and telescopes: XShooter on VLT 25 Next generation instruments and telescopes: Parameterss 26 Next generation instruments and telescopes: ELT et al. 27 Conclusions 28 Contents 29

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

Integral-Field Spectroscopy of SLACS Lenses Oliver Czoske Kapteyn Institute, Groningen, NL Three decades of gravitational lenses Symposium at the JENAM, 21-23 April 2009 Hatfield, 23 April 2009 Collaborators