OWLS Pipeline Status ReportOWLS Pipeline Status Report

STEP 2007 Workshop, JPLSTEP 2007 Workshop, JPLMon, Aug 20, 2007Mon, Aug 20, 2007

MSS Gill, J.Young, P. Martini, K. Honscheid, D. Weinberg, C. Kochanek + OWLS TeamMSS Gill, J.Young, P. Martini, K. Honscheid, D. Weinberg, C. Kochanek + OWLS Team( OWLS = OSU Weak Lensing Survey)( OWLS = OSU Weak Lensing Survey)

OutlineOutline

• Introduction to OWLS project• Description of hybrid approach• Our current results from deconvolving • Cuts on various sextractor quantities and

their effects on • Plans: Subaru images, LBT images

OWLS Project GoalsOWLS Project Goals

• Picture of Abell 611 from the LBT:

•Constraining cosmological parameters with •cluster weak lensing

LBT OWLS ProjectionsLBT OWLS Projections

• Projections for LBT with several clusters by next Autumn

(Plot: J. Yoo)

Assumes lensing using 50 richest clusters in observed 250 degree squared field with all background (lensed) galaxies at z=0.6

Colors are 1,2,3 sigma countours

Here: sigma_8 vs. Omega_m

Progress over the year..Progress over the year..

• We initially started the project thinking we would be able to pretty much use the shapelets code ‘out of the can’ to extract cluster shear

• But were never able to get minimal KSB estimator to give us the known shears for STEP2 fields; now know it has some instability

• So we ‘cooked up’ our own method to extract shear, which seems to work…

‘‘Hybrid’ ApproachHybrid’ Approach

• Seems slightly unorthodox, but we do it in 2 steps:

• For sextractor, we need to make pstamp recompositions of each object from shapelets

• Then separately sextract them

1. Deconvolve using shapelets 2. Extract ellipticity averages using

sextractor

Deconvolving with Extracted PSF Deconvolving with Extracted PSF • We used the STEP2 starfields for

the 6 individual psfs• Extract psf in the standard way:

pick stars, decompose them, fix beta and n_max, decompose again

• Constant psf not assumed

• We then deconvolved the galaxy field with this psf model

psf

Example of Deconvolved GalaxyExample of Deconvolved Galaxy

(From STEP2 field: psfD, file shear20, object #1)

From deconvolved fields to shear From deconvolved fields to shear extractionextraction

• Use standard approach of plotting the difference of extracted shear and the input shear, vs. the input shear, for a given field

• Fit this to a line, and extract output c (y-intercept) and m (slope) values

• Example (psfA):

Our Current Results – ADE AvgOur Current Results – ADE Avg Average of PSF’s A,D,E – compared with STEP2 groups

Squares = rotation-matched Triangles = original only Red square = our result

Our Current Results – PSF AOur Current Results – PSF A Squares = rotation-matched, Triangles = original only Red square = our result

Our Current Results – PSF DOur Current Results – PSF D Squares = rotation-matched, Triangles = original only Red square = our result

Our Current Results – PSF EOur Current Results – PSF E Squares = rotation-matched, Triangles = original only Red square = our result

PlansPlans

• Next: go to Subaru A1689 images

• Then to LBT images – currently have 2 clusters in hand

BACKUP SlidesBACKUP Slides

Results with Known PSFResults with Known PSF

• We initially used PSFs sent to us by J. Berge’ to get our technique working

• Example Plot of rotation-matched averaged c, m for D compared to paper, Red = ours

Cut effects on resultsCut effects on resultsMade cuts on several quantities (sexarea, sexflux,

a*b, shapelets error) and saw results improve• Example: change in m as function of

shapelets error cut: