The Zurich Extragalactic Bayesian Redshift Analyzer (ZEBRA) and its first application: COSMOS
Abstract
We present ZEBRA, the Zurich Extragalactic Bayesian Redshift Analyzer. 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: (1.) An automatic iterative technique to correct the original set of galaxy templates to best represent the SEDs of real galaxies at different redshifts; (2.) A training set of spectroscopic redshifts for a small fraction of the photometric sample; and (3.) 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 I_AB <= 22.5 COSMOS galaxies with available u*, B, V, g', r', i', z' and K_s photometry and zCOSMOS spectroscopic redshifts in the range 0 < z < 1.3. Adopting a 5-sigma-clipping that excludes less than 10 galaxies, both the Maximum Likelihood and Bayesian estimates for this sample have an accuracy dz/1+z better than 0.03. Similar accuracies are recovered using mock galaxies.
Cite
@article{arxiv.astro-ph/0609044,
title = {The Zurich Extragalactic Bayesian Redshift Analyzer (ZEBRA) and its first application: COSMOS},
author = {R. Feldmann and C. M. Carollo and C. Porciani and S. J. Lilly and P. Capak and Y. Taniguchi and O. Le Fevre and A. Renzini and N. Scoville and M. Ajiki and H. Aussel and T. Contini and H. McCracken and B. Mobasher and T. Murayama and D. Sanders and S. Sasaki and C. Scarlata and M. Scodeggio and Y. Shioya and J. Silverman and M. Takahashi and D. Thompson and G. Zamorani},
journal= {arXiv preprint arXiv:astro-ph/0609044},
year = {2009}
}
Comments
14 pages, 10 figures, some figures with reduced resolution, a high-resolution version can be obtained at http://www.exp-astro.phys.ethz.ch/ZEBRA/, accepted for publication in MNRAS