Publication Date:
2014-10-12
Description:
We present results from a study of the photometric redshift performance of the Dark Energy Survey (DES), using the early data from a Science Verification period of observations in late 2012 and early 2013 that provided science-quality images for almost 200 sq. deg. at the nominal depth of the survey. We assess the photometric redshift (photo- z ) performance using about 15 000 galaxies with spectroscopic redshifts available from other surveys. These galaxies are used, in different configurations, as a calibration sample, and photo- z 's are obtained and studied using most of the existing photo- z codes. A weighting method in a multidimensional colour–magnitude space is applied to the spectroscopic sample in order to evaluate the photo- z performance with sets that mimic the full DES photometric sample, which is on average significantly deeper than the calibration sample due to the limited depth of spectroscopic surveys. Empirical photo- z methods using, for instance, artificial neural networks or random forests, yield the best performance in the tests, achieving core photo- z resolutions 68 ~ 0.08. Moreover, the results from most of the codes, including template-fitting methods, comfortably meet the DES requirements on photo- z performance, therefore, providing an excellent precedent for future DES data sets.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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