1. Photometric redshift for clusters through A1689 and simulation studies Stephanie Jouvel, Ofer Lahav, Ole Host

2. Outline - Presentation of Le Phare code - A1689 photoz results : BPZ (Dan Coe) & Le Phare - Massimo Neghetti’s simulation : photoz results

3. Le Phare photoz code Stephane Arnouts & Olivier Ilbert : http://www.cfht.hawaii.edu/~arnouts/LEPHARE/cfht_lephare/lephare.html Interesting features and new developments include : - A prior on the redshift distribution using the VVDS spectroscopic redshift survey - Emission lines fluxes included in the library of templates. This is calculated using the relation between UV absolute magnitude – OII fluxes (Kennicutt et al. 1998). Other lines are derived from emission line ratios. - Possibility of including several extinction laws and E(B-V) values. - FIR scaling

4. Le Phare photoz code COSMOS photoz : Ilbert et al. 2009

5. A1689 photometric bands

6. A1689 : photoz BPZ & Le Phare COSMOS : 31 templates – Bruzual & Charlot 03 (Ext,NoEm) + Nz priori (VVDS)

7. Photoz results for A1689 Adding prior on the redshift distribution Error budget for HST filters probably underestimated : Filter calibration, source extraction Sextractor, photometry accuracy => High constraints on the fitting procedure We release it in adding +0.02 in quadrature to r,i,z HST filters photometric errors

8. Photoz results for A1689 : BPZ and Le Phare

9. A1689 photoz distribution Need to carefully select the filters to calculate photoz

10. Massimo's simulations : LePhare & BPZ

13. Massimo's simulations : lenses Contamination by galaxy cluster members : Photometry extraction problems Between Le Phare and BPZ we will probably Be able to remove catastrophic redshit

14. Conclusion - Validate the 0.02*(1+z) photoz accuracy - Remove catastrophic redshift using pdz information of several photoz codes - Need careful work on the photometry extraction - Do a proper analysis of the photometry error budget to improve the photoz accuracy - Optimize the observation strategy to get good photometry in the key filters - Do a pre-selection of cluster members from background galaxies following Umetsu et al. 2010 paper

15. Massimo's simulations : LePhare & BPZ

16. A1689 : 85 zpsec

17. Photoz results for A1689

18. Le Phare parameters

19. Photoz results for A1689 : dz

20. Massimo's simulations : LePhare vs BPZ

21. Massimo's simulations : LePhare & BPZ

22. Photoz results for A1689

23. Le Phare photoz code Jouvel et al. 2009 Why in one sentence

24. Improve photoz fit through error budget +0.02 Error budget for HST filters probably underestimated : Filter calibration, source extraction Sextractor, photometry accuracy => High constraints on the fitting procedure We release it in adding +0.02 in quadrature to r,i,z HST filters photometric errors