A short-timescale candidate microlensing event in the point-agape pixel lensing survey of M31

M. Auriere, P. Baillon, A. Bouquet, B.J. Carr, M. Creze, N.W. Evans, Y. Giraud-Heraud, A. Gould, P.C. Hewett, J. Kaplan, E. Kerins, E. Lastennet, Y. Le Du, A.L. Melchior, S.P. Henriksson, Stephen Smartt, D. Valls-Gabaud

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Abstract

We report the discovery of a short-duration microlensing candidate in the northern field of the POINT-AGAPE pixel lensing survey toward M31. Almost certainly, the source star has been identified on Hubble Space Telescope archival images, allowing us to infer an Einstein crossing time of t(E) = 10.4 days, a maximum magnification of A(max) similar to 18, and a lens-source proper motion mu (rel) > 0.3 mu as day(-1). The event has a projected separation of 8' from the center of M31, beyond the bulk of the stellar lens population. There are three plausible identifications/locations for the lensing object: a massive compact halo object (MACHO) in either M31 or the Milky Way, or a star in the M31 disk. The most probable mass is 0.06 M-. for an M31 MACHO, 0.02 M-. for a Milky Way MACHO, and 0.2 M-. for an M31 stellar lens. While the stellar interpretation is possible, the MACHO interpretation is the most probable for halo fractions above 20%.
Original languageEnglish
Pages (from-to)L137-L140
Number of pages4
JournalAstrophysical Journal
Volume553
Issue number2 PART 2
Publication statusPublished - 01 Jun 2001

ASJC Scopus subject areas

  • Space and Planetary Science

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    Auriere, M., Baillon, P., Bouquet, A., Carr, B. J., Creze, M., Evans, N. W., Giraud-Heraud, Y., Gould, A., Hewett, P. C., Kaplan, J., Kerins, E., Lastennet, E., Le Du, Y., Melchior, A. L., Henriksson, S. P., Smartt, S., & Valls-Gabaud, D. (2001). A short-timescale candidate microlensing event in the point-agape pixel lensing survey of M31. Astrophysical Journal, 553(2 PART 2), L137-L140.