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Photometric redshift for clusters through A1689 and simulation studies

Photometric redshift for clusters through A1689 and simulation studies. Stephanie Jouvel, Ofer Lahav, Ole Host. Outline. Presentation of Le Phare code A1689 photoz results : BPZ (Dan Coe) & Le Phare Massimo Neghetti’s simulation : photoz results. Le Phare photoz code.

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Photometric redshift for clusters through A1689 and simulation studies

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  1. Photometric redshift for clusters through A1689 andsimulation 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 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 Adding prior on the redshift distribution

  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

  11. Massimo's simulations : LePhare & BPZ

  12. Massimo's simulations : LePhare & BPZ

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

  14. 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 Conclusion

  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 Why in one sentence Jouvel et al. 2009

  24. Improve photoz fit through error budget 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 +0.02

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