1. Advisors: Tom Broadhurst, Yoel Rephaeli
Using “Weak Lensing Dilution” to Improve Measurements of Luminous and Dark Matter in A1689
Medezinski et al. 2007
Elinor Medezinski
Advisors: Tom Broadhurst, Yoel Rephaeli
Collaborators: Keiichi Umetsu, Narciso Benitez, Dan Coe, Holland Ford, Nobuo Arimoto, Xu Kong
Technion, July 25th 2007

2. Motivation Clusters mass - important cosmological tool
Mass distribution within clusters – cluster formation history
Probes of baryonic and dark matter
Cluster merger events – physical processes

3. Methods Measure mass and light of z<0.5 clusters with weak-lensing
Carefull cluster separation
Dilution effect
Combine strong, weak lensing analysis

4. Gravitational Lensing
The lens equation
Image
Source
Observer
Lens

5. A1689 Subaru SuprimeCam 34’x27’ HST ACS 3.3’x3.3’ Chandra ACIS 30’
Weak-lensing
A1689
z = 0.183
Subaru SuprimeCam 34’x27’
HST ACS 3.3’x3.3’
Chandra ACIS
Strong-lensing
30’
Arcs

6. Lensing Mapping
 - Shear
 - Convergence

7. a,b semi-major/minor axes
Weak Lensing Shear
Reduced shear – image ellipticity
a,b semi-major/minor axes

8. Weak Lensing Shear
Tangential shear – measured relative to cluster center

9. Color-magnitude
Red
Cluster sequence
E/SO sequence galaxies
Blue

10. Previous work
Weak-lensing profile for A1689, CFH12K, Bardeau et al. 2005
Use only magnitude-cut 21.6<R<24.7

11. Color-magnitude E/SO sequence galaxies Three galaxy samples
Red - background
Blue - faint background
Green – cluster +background
Red
Blue

12. Setting limits
Distortion reduces closer to the cluster sequence

13. Distortion of bright cluster galaxies, i<21.5 mag –
zero signal gT=0.0043

14. Weak Lensing Distortion
Background - Distortion declines gradually with radius
Green – distortion diluted by unlensed cluster members
The “Dilution” effect

15. Weak Lensing Distortion
ACS (r<2’) +Subaru
Saw-tooth pattern of strong lensing
Max – tangential critical curve, ~47’’
Min – radial critical curve, ~17’’

16. Fraction = Cluster Membership
Dilution to measure cluster membership
Correct for red/blue relative depths

17. Cluster Luminosity Profile
Cluster luminosity – “g-weighted” flux to get cluster flux
Flux  Luminosity
Linear fit

18. Cluster Color
Cluster color – “g-weighted” color
Bluer at large radii

19. M*/L vs. color from Bell et al. 2003
Mass to Light Ratio
High M/L ~ 480
Agrees with M/L inside 2’ from Broadhurst et al. 2005a
Mass estimates from lensing
M/M*
Mass profile from Broadhurst et al. 2005a,b
M*/L vs. color from Bell et al. 2003

20. Cluster Luminosity Function
Flat, no upturn

21. Distortion profile fits
NFW profile Best fit:
High concentration

22. Redshift magnification
Redshift decreases with cluster radius
Lensing magnification effect
Breaks the mass-sheet degeneracy
<z>

23. Lensing-Depth Relation
Background red galaxies are systematically less distorted than background blue
- Depth effect

24. The Capak catalog Multicolor images from Subaru of HDF-N 
photometric redshifts
Capak et al., 2004

25. Redshift distribution
Depth ratio

26. Weak Lensing scaling Can constrain cosmology from distortion ratio
Depend on cosmology:
Can constrain cosmology from distortion ratio =

27. Summary
Have determined light profile, color profile and radial luminosity functions of A1689 reliably, with no need to resolve the cluster sequence based on color.
Constructed flat luminosity function, with no need for far-field counts for background subtraction
Deduced high NFW concentration
Future work:
Obtain photo-z’s using more colors for consistency checks.
Extend to other clusters (CL0024,A370,A1703…) using existing Subaru and ACS data.
Constrain mass distribution by combining X-ray data and SZ effect.

28. Next Cluster – A1703