Observing Dark Worlds: A crowdsourcing experiment for dark matter mapping

Abstract We present the results and conclusions from the citizen science competition ‘Observing Dark Worlds’, where we asked participants to calculate the positions of dark matter halos from 120 catalogues of simulated weak lensing galaxy data, using computational methods. In partnership with Kaggle ( http://www.kaggle.com ), 357 users participated in the competition which saw 2278 downloads of the data and 3358 submissions. We found that the best algorithms improved on the benchmark code, LENSTOOL by > 30 % and could measure the positions of > 3 × 10 14 M ⊙ halos to 5 ″ and 10 14 M ⊙ to within 1 ′ . In this paper, we present a brief overview of the winning algorithms with links to available code.