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

• Published in: arXiv.org 2013-10
• Main Authors: Yee, J C, L -W Hung, Bond, I A, Allen, W, Monard, L A G, Albrow, M D, Fouque, P, Dominik, M, Tsapras, Y, Udalski, A, Gould, A, Bos, M, Christie, G W, Drummond, J, Gaudi, B S, Gorbikov, E, Klein, N, C -U Lee, Maoz, D, Natusch, T, B -G Park, Pogge, R W, Polishook, D, Shvartzvald, Y, Skowron, J, Thornley, G, The uFUN Collaboration, Abe, F, Bennett, D P, Botzler, C S, Chote, P, Freeman, M, Furusawa, K, Harris, P, Ling, C H, Masuda, K, Matsubara, Y, Miyake, N, Ohnishi, K, Rattenbury, N J, Saito, To, Sullivan, D J, Sumi, T, Suzuki, D, Sweatman, W L, Tristram, P J, Yock, P C M, Soszynski, I, Ulaczyk, K, Wyrzykowski, L, The OGLE Collaboration, Bachelet, E, Batista, V, Beatty, T G, J -P Beaulieu, Bennett, C S, Bowens-Rubin, R, Caldwell, J A R, Cassan, A, Cole, A A, Coutures, C, D Dominis Prester, Donatowicz, J, Henderson, C B, Kubas, D, J -B Marquette, Martin, R, Menzies, J W, Shappee, B, Williams, A, Wouters, D, J van Saders, Zub, M, The PLANET Collaboration, Street, R A, Horne, K, Steele, I A, The RoboNet Collaboration, Burgdorf, M J, Gerner, T, Hardis, S, Harpsoe, K, Hessman, F V, Hinse, T C, Hundertmark, M, Jorgensen, U G, Kerins, E, Liebig, C, Mancini, L, Mathiasen, M, Rahvar, S, Ricci, D, Sahu, K C, Scarpetta, G, Schafer, S, Schonebeck, F, Snodgrass, C, Southworth, J, Surdej, J, Wambsgans, J
• Format: Article
• Language: English
• Subjects: Extrasolar planets; Lenses; Microlenses; Planet detection
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1210.6041

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.