Star-galaxy classification in the Dark Energy Survey Y1 data set
Bechtol, K.; Smith, M.; Allam, S.; Bertin, E.; Brooks, D.; Carretero, J.; Davis, C.; Desai, S.; Doel, P.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Gruen, D.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; Kuehn, K.; Li, T. S.; Lima, M.; Maia, M. A. G.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Plazas, A. A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.; DES Collaboration; Choi, A.; Balbinot, E.; Hollowood, D. L.; Jeltema, T.; Lahav, O.; March, M.; Thomas, D.; Garcia-Bellido, J.; Banerji, M.; Drlica-Wagner, A.; Fernandez, E.; Giannantonio, T.; Hoyle, B.; Krause, E.; Nord, B.; Yanny, B.; de Vicente, J.; Santiago, B.; Tucker, D. L.; Wester, W.; McMahon, R. G.; Ross, A. J.; Sheldon, E.; Abbott, T.; Aleksić, J.; Gruendl, R.; Marchã, M. J.; Soumagnac, M. T.; Abdalla, F.; Avestruz, C.; Bonnett, C.; Brunner, R.; Carrasco-Kind, M.; Kim, E.; Moraes, B.; Wei, K.; Carnero-Rosell, A.; Cunha, C.; da Costa, L.; James, D.; Kirk, D.
Spain, Germany, United Kingdom, Israel, United States, South Africa, France, Brazil, Chile, India, Australia
Abstract
We perform a comparison of different approaches to star-galaxy classification using the broad-band photometric data from Year 1 of the Dark Energy Survey. This is done by performing a wide range of tests with and without external `truth' information, which can be ported to other similar data sets. We make a broad evaluation of the performance of the classifiers in two science cases with DES data that are most affected by this systematic effect: large-scale structure and Milky Way studies. In general, even though the default morphological classifiers used for DES Y1 cosmology studies are sufficient to maintain a low level of systematic contamination from stellar misclassification, contamination can be reduced to the O(1 per cent) level by using multi-epoch and infrared information from external data sets. For Milky Way studies, the stellar sample can be augmented by {∼ }20{{ per cent}} for a given flux limit. Reference catalogues used in this work are available at http://des.ncsa.illinois.edu/releases/y1a1.