MOA-2010-BLG-311: A planetary candidate below the threshold of reliable detection
astro-ph.EP
/ Authors
J. C. Yee, L. -W. Hung, I. A. Bond, W. Allen, L. A. G. Monard, M. D. Albrow, P. Fouque, M. Dominik, Y. Tsapras, A. Udalski
and 116 more authors
A. Gould, R. Zellem, M. Bos, G. W. Christie, D. L. DePoy, Subo Dong, J. Drummond, B. S. Gaudi, E. Gorbikov, C. Han, S. Kaspi, N. Klein, C. -U. Lee, D. Maoz, J. McCormick, D. Moorhouse, T. Natusch, M. Nola, B. -G. Park, R. W. Pogge, D. Polishook, A. Shporer, Y. Shvartzvald, J. Skowron
/ Abstract
We analyze MOA-2010-BLG-311, a high magnification (A_max>600) microlensing event with complete data coverage over the peak, making it very sensitive to planetary signals. We fit this event with both a point lens and a 2-body lens model and find that the 2-body lens model is a better fit but with only Delta chi^2~80. The preferred mass ratio between the lens star and its companion is $q=10^(-3.7+/-0.1), placing the candidate companion in the planetary regime. Despite the formal significance of the planet, we show that because of systematics in the data the evidence for a planetary companion to the lens is too tenuous to claim a secure detection. When combined with analyses of other high-magnification events, this event helps empirically define the threshold for reliable planet detection in high-magnification events, which remains an open question.