Star–galaxy classification in the Dark Energy Survey Y1 data set

• Published in: Monthly notices of the Royal Astronomical Society Vol. 481; no. 4; pp. 5451 - 5469
• Main Authors: Sevilla-Noarbe, I., Hoyle, B., Marchã, M.J., Soumagnac, M.T., Bechtol, K., Drlica-Wagner, A., Abdalla, F., Aleksić, J., Avestruz, C., Balbinot, E., Banerji, M., Bertin, E., Bonnett, C., Brunner, R., Carrasco-Kind, M., Choi, A., Giannantonio, T., Kim, E., Lahav, O., Moraes, B., Nord, B., Ross, A.J., Rykoff, E.S., Santiago, B., Sheldon, E., Wei, K., Wester, W., Yanny, B., Abbott, T., Allam, S., Brooks, D., Carnero-Rosell, A., Carretero, J., Cunha, C., da Costa, L., Davis, C., de Vicente, J., Desai, S., Doel, P., Fernandez, E., Flaugher, B., Frieman, J., Garcia-Bellido, J., Gaztanaga, E., Gruen, D., Gruendl, R., Gschwend, J., Gutierrez, G., Hollowood, D.L., Honscheid, K., James, D., Jeltema, T., Kirk, D., Krause, E., Kuehn, K., Li, T.S., Lima, M., Maia, M.A.G., March, M., Mcmahon, R.G., Menanteau, F., Miquel, R., Ogando, R.L.C., Plazas, A.A., Sanchez, E., Scarpine, V., Schindler, R., Schubnell, M., Smith, M., Smith, R.C., Soares-Santos, M., Sobreira, F., Suchyta, E., Swanson, M.E.C., Tarle, G., Thomas, D., Tucker, D.L., Walker, A.R.
• Format: Journal Article
• Language: English
• Published: Oxford University Press (OUP): Policy P - Oxford Open Option A 01.12.2018
• Subjects: Astrophysics; Instrumentation and Detectors; Physics; Techniques: photometric; Methods: statistical; Methods: data analysis
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/sty2579

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 |${\sim }20{{\ \rm per\ cent}}$| for a given flux limit. Reference catalogues used in this work are available at des.ncsa.illinois.edu/releases/y1a1.