1. Full strength of (weak) Cluster lensing
Elinor Medezinski
Tel Aviv University
Medezinski et al. 2007, Broadhurst et al. 2008,
Medezinski et al. 2009, Medezinski et al (in prep)
Advisors: Tom Broadhurst, Yoel Rephaeli
Collaborators: Keiichi Umetsu, Narciso Benitez, Dan Coe,
Holland Ford, Masamune Oguri

2. Color-magnitude, A1689 (Medezinski et al. 2007) E/SO sequence galaxies
Three galaxy samples
Red – background. (redder than sequence)
Blue – faint background. (determine by comparing WL signal to red)
Green – cluster +background
Set magnitude limit to 26.5 to avoid incompleteness
(Medezinski et al. 2007)
Red
Blue

3. New approach - Color-Color
B,R,z’ for A370
V,R,z’ for RXJ1347
g’,r’,i’ for A1703
(Medezinski et al. 2009)
Galaxy number density map
4 Density peaks – different galaxy populations
A370

4. Average radius in Color-Color space
Color code = distance from cluster center
Blue = low mean radius – cluster galaxies
A370

5. Sample selection in Color-Color
Red – background
Blue – background
Green – cluster +~background
Pink – foreground +background

6. Weak lensing profiles “Dilution” method gT profiles –
rising background signal
~zero for green – diluted by unlensed cluster members
A370
Red – background
Blue – background
Green – cluster +~background
Pink – foreground +background
Weak lensing measured using IMCAT (Umetsu & Broadhurst 2008, Umetsu, Medezinski et al. 2010)
“Dilution” method
Cluster membership – almost ~100% for entire radius range,
→green sample is comprised mostly of cluster.

7. Foreground contamination
Density profiles –
foreground shows homogeneous distribution, like background,
unlike cluster which is concentrated.
A370
Red – background
Blue – background
Green – cluster +~background
Pink – foreground +background
gT profiles –
foreground also shows diluted signal relative to background

8. Dilution in other work Oguri et al. 2009
Diluted by a factor of ~2 in the center
Leads to underestimated Einstein radius
Leads to underestimated Cvir
A1703

9. 2D Mass reconstruction + Round, ~relaxed massive clusters Weak-lensing
galaxy # density
Round, ~relaxed massive clusters
Broadhurst et al. 2008

10. NFW fits give high concentrations (Cvir=rvir/rs)
Broadhurst et al. 2008
gT-profiles agree
NFW fits give high concentrations (Cvir=rvir/rs)
than expected by ΛCDM N-body simulations
Use magnification to check consistency of gT results

11. NFW parameters Cvir-Mvir comparison with other studies and ΛCDM
4σ discrepancy with ΛCDM, even considering orientation and selection bias (Hennawi et al 2007, Oguri & Blanford et al. 2009)

12. Luminosity & M/L profiles
A1689
A1703
A370
RXJ
Cluster luminosity – “g-weighted” flux to get cluster flux
Flux  Luminosity
Linear fit
M/L goes down in the outskirts – morphology-density related effect (Dressler 1980)

13. M/L profiles M/L goes down in the center – luminous BCGs
M/L goes down in the outskirts –morphology-density relation (Dressler 1980)
A1689
A1703
A370
RXJ

14. Cluster Luminosity Function – A1689
Flat faint-end, no upturn

15. Lensing distance vs. redshift:
Weak lensing strength vs. redshift test of cosmology using WL distortions (Medezinski et al in prep)
In the weak limit,
Lensing distance vs. redshift:

16. Weak lensing samples
Select background galaxy samples –”red”, “blue”, “green” and “dropouts” and measure their lensing profile
Red – background
Blue – background
Green – background
Pink – background (high-z dropouts)
A370

17. Fit background WL distortion profile with power law:
Bright
Red – background
Blue – background
Green – background
Pink – background (high-z dropouts)
Fit background WL distortion profile with power law:
Find amplitude ai for other samples, with same power law
Faint

18. COSMOS Redshifts
30-band wide field (2 sq. deg.) survey (Capak et al. 2007)
Photometric redshifts catalog (Ilbert et al. 2009)
mean redshift in color-color space
Same selection samples

19. Results:
Faint
Bright
gT amplitude vs. redshift overlaid on the lensing distance – redshift curves
A370
ZwCl
RXJ

20. Summary
Developed new scheme to resolve cluster/foreground/background selected in color-color space and better determine weak lensing profiles.
Determined light profiles & radial luminosity functions of A1689, A1703, A370, RXJ1347 reliably, with no need to resolve the cluster sequence based on color.
Found flat luminosity function, with no need for far-field counts for background subtraction.
Constructed M/L profiles to the virial radius, showing physical behavior of DM to light distributions, dropping to the center of cluster, and also dropping to the outskirts.
Deduced high NFW concentrations, contradicting ΛCDM simulation expectation values.
Use weak lensing distortions to constrain the lensing distance – redshift relation.
Future work:
Obtain photo-z’s using more colors for consistency checks.
Extend to other clusters (CL0024 submitted Umetsu et al. 2009, MACS sample) using existing Subaru.
Combine w/ strong-lensing from HST/ACS (Zitrin et al. 2009) – Hubble MCT proposal accepted!! – 25 clusters with 525 orbits.
Constrain mass distribution by combining X-ray and SZ from Chandra and Amiba (Amiba paper - Umetsu et al. 2009).