Galactic bulge microlensing events from the MACHO collaboration

C.L. Thomas, K. Griest, P. Popowski, K.H. Cook, A.J. Drake, D. Minniti, D.G. Myer, C. Alcock, R.A. Allsman, D.R. Alves, T.S. Axelrod, A.C. Becker, D.P. Bennett, K.C. Freeman, M. Geha, M.J. Lehner, S.L. Marshall, C.A. Nelson, B.A. Peterson, Peter QuinnC.W. Stubbs, W. Sutherland, T. Vandehei, D.L. Welch

    Research output: Contribution to journalArticle

    21 Citations (Scopus)

    Abstract

    We present a catalog of 450 relatively high signal-to-noise ratio microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields, and as expected, they show a clear concentration toward the Galactic center. No optical depth is given for this sample, since no blending efficiency calculation has been performed and we find evidence for substantial blending. In a companion paper we give optical depths for the subsample of events on clump giant source stars, where blending is a less significant effect. Several events with sources that may belong to the Sagittarius dwarf galaxy are identified. For these events even relatively low dispersion spectra could suffice to classify these events as either consistent with Sagittarius membership or as non-Sagittarius sources. Several unusual events, such as microlensing of periodic variable source stars, binary lens events, and an event showing extended source effects, are identified. We also identify a number of contaminating background events as cataclysmic variable stars.
    Original languageEnglish
    Pages (from-to)906-934
    JournalThe Astrophysical Journal
    Volume631
    Issue number2
    DOIs
    Publication statusPublished - 2005

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