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CLASH Photometric redshifts for galaxies in cluster field

CLASH Photometric redshifts for galaxies in cluster field. Stephanie Jouvel & CLASH photo- z team. Jouvel et al 2013 submitted. CLASH/HST Photo- z goals. Accurate photo- z for the SL arcs Clean cluster/background galaxy selection. 690 galaxies with spec- z covered by HST:

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CLASH Photometric redshifts for galaxies in cluster field

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  1. CLASH Photometric redshifts for galaxies in cluster field Stephanie Jouvel & CLASH photo-z team Jouvel et al 2013 submitted Stephanie Jouvel

  2. CLASH/HST Photo-z goals • Accurate photo-z for the SL arcs • Clean cluster/background galaxy selection 690 galaxies with spec-z covered by HST: 584 cluster+foreground 106 lensed background We use BPZ & Le Phare Not enough galaxies to train NN and other training methods Stephanie Jouvel

  3. COSMOS templates library for Le Phare Lines are templates colors, dots are CLASH observations for the full specz sample Good agreement between model & the CLASH observations Stephanie Jouvel

  4. Lensed background galaxies z>zcluster+0.2 Very good accuracy of NMAD~3% Stephanie Jouvel

  5. Foreground+cluster galaxies z<zcluster+0.2 Stephanie Jouvel

  6. Photo-z scatter for full spec-z sample Stephanie Jouvel

  7. CLASH photoz accuracy with simulations Simulation of the CLASH photometry in the 16 HST filters We reach a limit in the photo-z scatter due to the filter resolution => It’ll be hard to beat the 2-3% NMAD using broadband photometry Stephanie Jouvel

  8. MACS1206 strong-lensing arcs 4 systems with spec-z: Sys 1: zs=1.03 Sys 2: zs=3.03 Sys 3: zs=3.03 Sys 4: zs=2.54 Stephanie Jouvel

  9. MACS1206 System 1 Balmer break Lyman break Zs=1.03: Balmer & Lyman break => Good photoz Stephanie Jouvel

  10. MACS1206 System 2 Lyman break Zs=3.03: Balmer break outside the CLASH filters Stephanie Jouvel

  11. MACS1206 System 3 Lyman break Zs=3.03: Balmer break outside the CLASH filters Stephanie Jouvel

  12. MACS1206 System 4 Balmer break Lyman break Cluster light contamination Zs=2.54: Balmer & Lyman break => Good photoz Stephanie Jouvel

  13. UV filters in the photoz estimation of background lensed galaxies • UVIS filters are useful to follow the Lyman break for galaxies 0.7<z<2.5 • At z>2.5 the Lyman break is in F435W and the UVIS filters stop being useful. • At z<0.7 the Lyman break did not reach F225W • UVIS filters useful for the photo-z of background galaxies Stephanie Jouvel

  14. Photoz scatter & LSS in lensing Translating a 4% photoz error into a SL arcs positional error when deriving gravitational potential on A1689 (cause it has more than 106 arcs). A 4% photoz error is bigger than LSS positional error for 6/106 arcs. => 3% photoz error is ok for SL Stephanie Jouvel

  15. BPZ and Le Phare Some work needed to understand the discrepancy at low z between BPZ and Le Phare Stephanie Jouvel

  16. BPZ and Le Phare Some work needed to understand the discrepancy at low z between BPZ and Le Phare: Low odds are lowz for Le Phare and highz for BPZ Stephanie Jouvel

  17. Some ideas Stephanie Jouvel

  18. Conclusion • Good photoz accuracy for the SL arcs from both BPZ and Le Phare of NMAD~3% • Progress needed for the background/foreground galaxy selection. BPZ and Le Phare have different estimates for 7% of galaxies in MACS1206 field • Use the full P(z) to improve the photoz estimates Stephanie Jouvel

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