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The Zurich Extragalactic Bayesian Redshift Analyzer and its first application: COSMOS

Feldmann, R. ; Carollo, C. M. ; Porciani, C. ; Lilly, S. J. ; Capak, P. ; Taniguchi, Y. ; Fèvre, O. Le ; Renzini, A. ; Scoville, N. ; Ajiki, M. ; Aussel, H. ; Contini, T. ; McCracken, H. ; Mobasher, B. ; Murayama, T. ; Sanders, D. ; Sasaki, S. ; Scarlata, C. ; Scodeggio, M. ; Shioya, Y. ; Silverman, J. ; Takahashi, M. ; Thompson, D. ; Zamorani, G.

In: Monthly Notices of the Royal Astronomical Society, 2006, vol. 372, no. 2, p. 565-577

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    Title
    • The Zurich Extragalactic Bayesian Redshift Analyzer and its first application: COSMOS
    Author
    • Feldmann, R.. Institute of Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
    • Carollo, C. M.. Institute of Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
    • Porciani, C.. Institute of Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
    • Lilly, S. J.. Institute of Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
    • Capak, P.. California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125, USA
    • Taniguchi, Y.. Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720, USA
    • Fèvre, O. Le. Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, France
    • Renzini, A.. Dipartimento di Astronomia, Universitá di Padova, vicolo dell'Osservatorio 2, I-35122 Padua, Italy
    • Scoville, N.. California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125, USA
    • Ajiki, M.. Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
    • Aussel, H.. Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, HI 96822, USA
    • Contini, T.. Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrnes, Toulouse, France
    • McCracken, H.. Institut d'Astrophysique de Paris, Universitè Pierre et Marie Curie, 75014 Paris, France
    • Mobasher, B.. Space Telescope Science Institute, 3700 San Martin Drive, MD 21218, USA
    • Murayama, T.. Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
    • Sanders, D.. Institute for Astronomy, 2680 Woodlawn Dr., University of Hawaii, Honolulu, HI 96822, USA
    • Sasaki, S.. Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
    • Scarlata, C.. Institute of Astronomy, Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
    • Scodeggio, M.. INAF - IASF Milano, Italy
    • Shioya, Y.. Physics Department, Graduate School of Science and Engineering, Ehime University, Japan
    • Silverman, J.. Max Planck Institut fr Extraterrestrische Physik, Garching, Germany
    • Takahashi, M.. Astronomical Institute, Graduate School of Science, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan
    • Thompson, D.. California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125, USA
    • Zamorani, G.. INAF Osservatorio Astronomico di Bologna, Italy
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:301721
    Summary
    We present the Zurich Extragalactic Bayesian Redshift Analyzer (zebra). The current version of zebra combines and extends several of the classical approaches to produce accurate photometric redshifts down to faint magnitudes. In particular, zebra uses the template-fitting approach to produce Maximum Likelihood and Bayesian redshift estimates based on the following points. An automatic iterative technique to correct the original set of galaxy templates to best represent the Spectral Energy Distributions (SEDs) of real galaxies at different redshifts. A training set of spectroscopic redshifts for a small fraction of the photometric sample to improve the robustness of the photometric redshift estimates. An iterative technique for Bayesian redshift estimates, which extracts the full two-dimensional redshift and template probability function for each galaxy. We demonstrate the performance of zebra by applying it to a sample of 866 IAB≤ 22.5 COSMOS galaxies with available u*, B, V, g′, r′, i′, z′ and Ks photometry and zCOSMOS spectroscopic redshifts in the range 0 < z < 1.3. Adopting a 5σ clipping that excludes ≤10 galaxies, both the Maximum Likelihood and Bayesian zebra estimates for this sample have an accuracy σΔz/(1+z) smaller than 0.03. Similar accuracies are recovered using mock galaxies. zebra is made available at http://www.exp-astro.phys.ethz.ch/ZEBRA