INTERPRETATION OF STRONG SHORT-TERM CENTRAL PERTURBATIONS IN THE LIGHT CURVES OF MODERATE-MAGNIFICATION MICROLENSING EVENTS

C. Han, K.H. Hwang, D. Kim, A. Udalski, F. Abe, L.A.B. Monard, J. Mccormick, M.K. Szymanski, M. Kubiak, G. Pietrzynski, I. Soszynski, O. Szewczyk, L. Wyrzykowski, K. Ulaczyk, I.A. Bond, C.S. Botzler, A. Fukui, K. Furusawa, J.B. Hearnshaw, Y. Itow & 70 others K. Kamiya, P.M. Kilmartin, A. Korpela, W. Lin, C.H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, K. Ohnishi, T. Tokumura, Y.C. Perrott, N. Rattenbury, T. Saito, T. Sako, L. Skuljan, D.S. Sullivan, T. Sumi, W.L. Sweatman, P.J. Tristram, P.C.M. Yock, W. Allen, G.W. Christie, D.L. Depoy, S. Dong, B.S. Gaudi, A. Gould, C.U. Lee, T. Natusch, B.G. Park, R.W. Pogge, M.D. Albrow, A. Allan, V. Batista, J.P. Beaulieu, D.P. Bennett, S. Brillant, M. Bode, D.M. Bramich, M. Burgdorf, J.A.R. Caldwell, H. Calitz, A. Cassan, E. Corrales, S. Dieters, D.D. Prester, M. Dominik, J. Donatowicz, P. Fouque, J. Greenhill, K. Hill, M. Hoffman, K. Horne, U.G. Jorgensen, N. Kains, D. Kubas, J.B. Marquette, R. Martin, P. Meintjes, J. Menzies, K.R. Pollard, K.C. Sahu, C. Snodgrass, I. Steele, R. Street, Y. Tsapras, J. Wambsganss, Andrew Williams, M. Zub

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    Abstract

    To improve the planet detection efficiency, current planetary microlensing experiments are focused on highmagnificationevents searching for planetary signals near the peak of lensing light curves. However, it is known that central perturbations can also be produced by binary companions and thus it is important to distinguish planetarysignals from those induced by binary companions. In this paper, we analyze the light curves of microlensingevents OGLE-2007-BLG-137/MOA-2007-BLG-091, OGLE-2007-BLG-355/MOA-2007-BLG-278, and MOA-2007-BLG-199/OGLE-2007-BLG-419, for all of which exhibit short-term perturbations near the peaks of the lightcurves. From detailed modeling of the light curves, we find that the perturbations of the events are caused by binarycompanions rather than planets. From a close examination of the light curves combined with the underlying physicalgeometry of the lens system obtained from modeling, we find that the short timescale caustic-crossing featureoccurring at a low or a moderate base magnification with an additional secondary perturbation is a typical featureof binary-lens events and thus can be used for the discrimination between the binary and planetary interpretations.
    Original languageEnglish
    Pages (from-to)1116-1121
    JournalThe Astrophysical Journal
    Volume705
    Issue number2
    DOIs
    Publication statusPublished - 2009

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