ARE THE OGLE MICROLENSES IN THE GALACTIC BAR

被引:81
作者
PACZYNSKI, B
STANEK, KZ
UDALSKI, A
SZYMANSKI, M
KALUZNY, J
KUBIAK, M
MATEO, M
KRZEMINSKI, W
机构
[1] UNIV WARSAW,PL-00478 WARSAW,POLAND
[2] UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109
[3] LAS CAMPANAS OBSERV,CARNEGIE OBSERV,LA SERENA,CHILE
关键词
DARK MATTER; GALAXY; CENTER; STRUCTURE; GRAVITATIONAL LENSING; STARS; LOW-MASS; BROWN DWARFS;
D O I
10.1086/187607
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The analysis of the first 2 years of data from the Optical Gravitational Lensing Experiment (OGLE) project revealed nine microlensing events of the Galactic bulge stars, with the characteristic timescales in the range 8.6 days < t(0) < 62 days, where t(0) = R(E)/V. The optical depth to microlensing is larger than (3.3 +/- 1.2) x 10(-6), in excess of current theoretical estimates, indicating a much higher efficiency for microlensing by either bulge or disk lenses. We argue that the lenses are likely to be ordinary stars in the Galactic bar, which has its long axis elongated toward us. A relation between t, and the lens masses remains unknown until a quantitative model of bar microlensing becomes available. At this time we have no evidence that the OGLE events are related to dark matter. The geometry of lens distribution can be determined observationally when the microlensing rate is measured over a large range of Galactic longitudes, like -10 degrees < l < 10 degrees, and the relative proper motions of the Galactic bulge (bar) stars are measures with the Hubble Space Telescope.
引用
收藏
页码:L113 / L116
页数:4
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