1210.6041 (J. C. Yee et al.)

MOA-2010-BLG-311: A planetary candidate below the threshold of reliable detection    [PDF]

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, A. Gould, R. Zellem, the MicroFUN, MOA, OGLE, PLANET, RoboNet Collaborations, the MiNDSTEp Consortium

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^2~140. 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.

View original: http://arxiv.org/abs/1210.6041