Surveys with OmegaCAM / VST KIDS Koen Kuijken, Leiden

ESO public survey proposal –Accepted as core survey (May) 1700 square degrees ~ 400 nights Sloan band survey, median redshift 0.8 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 samples KIDS: Kilo-Degree Survey

Overlaps: –UKIDSS –SDSS –2dFGRS –CFHLS –COSMOS 960 sq deg. 2dFGRS SDSS DR2 CFHLS KIDS (Leiden, Groningen, Munchen, Bonn, Paris, Naples, Imperial, Edinburgh, Cambridge)

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

Post-PSP field layout

Integration times, sensitivities Use all moon phases, best 80% of seeing <0.7” (40%) ” (20%) ” (20%) Dark (50%)r’g’u’ Grey (15%)i’ Bright (35%)z’ filterExp time (s) Medn seeing (“) 5-  2” AB u’ g’ r’ i’ z’ TOT7200 Optimize for weak lensing Wide-i VISTA

KIDS vs. SDSS

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

‘w’ (weak lensing) Weak lensing constraints –Lensing effect depends on relative distances of source and lens –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!

‘w’ (wiggles) 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=1.0 z=1.4 Angular waveno. (deg -1 )

Photo-z from KIDS/UKIDSS r<23.5 r<24 r<250<z<6 0<z<1.5

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

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 z>6.4 Many fainter z~5-6

The challenges Distributed dataprocessing (ASTRO-WISE!) –Work in a KIDS context –Central monitoring of calibration –Quality control is the key: Some overlaps between teams  intercompare Version control of the procedures, parameters, etc. Advanced QC tools, incl lensing and photo-z –Integration with ‘static’ IR surveys (VISTA, UKIDSS) Image and catalogue level

The challenges II Lensing measurements with shapelets Photo-z : matched-PSF and matched- aperture photometry for colors Shapelets session at 3pm.

SUMMARY 1700 sq.deg.: –Equatorial strip = UKIDSS / 2dFGRS area –South Galactic Pole = 2dFGRS field VISTA!! 5-band u’g’r’i’z’ Integration time 2hrs per field  440 nts Use range of seeing conditions, moon phase Optimized for weak lensing survey –Other applications: large-scale structure, cluster evolution, galaxy evolution, …

Shears from shapelets