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Exploring the Universe with Kilo-Degree Survey Weak Lensing

Learn about Kilo-Degree Survey from Konrad Kuijken using telescopes and detectors to map the universe with weak lensing. Discover its goals including halo structure, dark energy, galaxy evolution, and more. Explore the impact of weak lensing on galaxy types and redshifts.

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Exploring the Universe with Kilo-Degree Survey Weak Lensing

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  1. KIDS: mapping the universe with weak lensingKonrad Kuijken, Leiden

  2. VISTA 4m telescope 0.6 sq.deg. IR camera 16 2kx2k detectors 0.35” pixels VST 2.6m telescope 1 sq.deg. optical camera (OmegaCAM) 32 2kx4k detectors 0.21” pixels

  3. 60 b=45 30 -75 b=-60 1500 sq.deg. in ugriZYJHK +2000 sq.deg. in i (+UKIDSS YJHK)

  4. KIDS vs. SDSS, CFHTLS (M.Neeser)

  5. KIDS: Kilo-Degree Survey • ESO Public Survey • Goals: • Halo structure (weak lensing) • Dark energy (w via ang. power spec; wk lensing) • Galaxy evolution vs. environment • Cluster searches • Higher-redshift quasars than SDSS • White dwarf searches

  6. Galaxy-galaxy lensing 45 sq. deg from RCS survey (Hoekstra, Yee, Gladders 2004) Galaxy-mass correlation Halo radii Halo shapes KIDS: 7x smaller errors (#pairs) Good photo-z’s (b/g), spectroscopic z’s (lenses) Study effect by galaxy type

  7. ‘w’ (weak lensing) • Weak lensing constraints • Lensing effect depends on relative distances of source and lens:  Dls/Ds • Measure lensing strength as function of redshift • Deduce distance as function of redshift • Geometrical test of expansion history: w (5%) • Needs well-controlled photo-z’s!

  8. ‘w’ (wiggles) (P. Schuecker) • Use scale of power spectrum wiggles as standard candle • Spec redshift surveys: need few 100,000 gals for detection • Photometric redshift surveys: wash out z information, but many more galaxies! • KIDS: 67,000,000 gals with r<23.5 (20- fluxes) • Photo-z accurate to 0.03(1+z) (ugrizYJHK) • w(z=0) to <15% from KIDS • w(z=1) to better accuracy z=0.6 z=1.0z=1.4 Angular waveno. (deg-1)

  9. Effect of w • Angular diameter distances changes • Lensing measures • Baryon oscillations measure dA(z)

  10. Effect of w

  11. Photo-z from KIDS/UKIDSS (Saglia) r<23.5 r<24r<25 0<z<6 0<z<1.5 Scatter further reduced with deeper IR data

  12. Typical SED’s (r~24, redshift~1) • KIDS ugriz • UKIDS YJHK

  13. Data Flow (E. Valentijn) • Spread over 6 data centers in Europe • Astro-WISE system = federated database + query-driven pipeline processing • Db-wide control of calibration and quality ctl. • Mini-VO with a mini-GRID • Integration with UKIDSS / VISTA IR data • Data delivery will be to ESO

  14. Multi-band photometry • Accurate colours for photo-z: need PSF and aperture matching • Classically: reconvolve all images to common (worst?) seeing, then perform aperture photometry on all • New approach: compute all fluxes for a small set of standard PSFs and apertures • Can do this catalogue-based, eg via shapelets • Match surveys with diff’t pixel scales, etc.

  15. KIDS: the kilo-degree survey • About 8 TB of reduced image pixels • 40TB of raw data • 440 nights of observing time • VO-like work plan (federated database environment Astro-WISE) • ‘Natural’ survey speed for VST / OmegaCAM, and VISTA • Fits nicely between SDSS/UKIDSS-LAS and CFHTLS-WIDE: • SDSS: • deeper (2 mag), narrower (5x) • finer image quality (2x) • cf. CFHLS: • wider (9x), shallower (1 mag) • comparable/better(?) image quality • Includes near-IR  stellar mass; photo-z’s; highest redshifts; … • Spectra from 2dFGRS & SDSS  know the foreground structure

  16. z>6.4 QSOs • Combine with IR (UKIDSS, VISTA) • Look for IR objects faint in i or z • Find brown dwarfs and high-z QSOs • Expect ~7 @ z>6.4 • Many fainter z~5-6

  17. Lensing / photo-z survey • VST/OmegaCAM: 1 sq deg, 2.6m telescope • VISTA/VISTACAM: 0.6 sqdeg, 4m telescope • 1500 sq.deg. of ugri (~400n VST) + ZYJHK (~200n VISTA) • Deeper in r, with good seeing • VST 2m deeper than SDSS (1m shallower than CFHTLS) • VISTA 1.5m deeper than UKIDSS

  18. KIDS(Leiden, Groningen, Munchen, Bonn, Paris, Naples, Imperial, Edinburgh, Cambridge) 60 b=45 30 • Overlaps: • UKIDSS • SDSS • 2dFGRS • CFHLS • COSMOS • AA • 780 sq deg. CFHLS 2dFGRS SDSS/UKIDSS LAS

  19. KIDS(Leiden, Groningen, Munchen, Bonn, Paris, Naples, Imperial, Edinburgh, Cambridge) • Overlaps: • 2dFGRS • VISTA! • 720 sq deg. • Perfect for VLT and AAT, APEX, ALMA 2dFGRS

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