photometric redshift for clusters through a1689 and simulation studies
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Photometric redshift for clusters through A1689 andsimulation 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
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
Le Phare photoz code
COSMOS photoz : Ilbert et al. 2009
A1689 photometric bands
A1689 : photoz BPZ & Le PhareCOSMOS : 31 templates – Bruzual & Charlot 03 (Ext,NoEm) + Nz priori (VVDS)
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
Photoz results for A1689 : BPZ and Le Phare
A1689 photoz distribution
Need to carefully select the filters to calculate photoz
Massimo's simulations : LePhare & BPZ
Massimo's simulations : LePhare & BPZ
Massimo's simulations : LePhare & BPZ
Massimo's simulations : lenses
Contamination by galaxy cluster members :Photometry extraction problems
Between Le Phare and BPZ we will probablyBe able to remove catastrophic redshit
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
Massimo's simulations : LePhare & BPZ
A1689 : 85 zpsec
Photoz results for A1689
Le Phare parameters
Photoz results for A1689 : dz
Massimo's simulations : LePhare vs BPZ
Massimo's simulations : LePhare & BPZ
Photoz results for A1689
Le Phare photoz code
Jouvel et al. 2009
Why in one sentence
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