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We investigate the possibility of determining whether microlensing objects towards the Large Magellanic Cloud (LMC) are in a Galactic thick disc, or are in a Galactic halo, by using parallax measurements with an Earth-radius scale baseline.…

Astrophysics · Physics 2009-11-07 T. Sumi , Y. Kan-ya

We report on the identification of the lens responsible for microlensing event MACHO-LMC-20. As part of a \textit{Spitzer}/IRAC program conducting mid-infrared follow-up of the MACHO Large Magellanic Cloud microlensing fields, we discovered…

Spitzer microlensing parallax observations of OGLE-2015-BLG-1212 decisively breaks a degeneracy between planetary and binary solutions that is somewhat ambiguous when only ground-based data are considered. Only eight viable models survive…

Over the past decade, microlensing has developed into a powerful tool to study stellar astrophysics, especially stellar atmospheres, stellar masses, and binarity. I review this progress. Stellar atmospheres can be probed whenever the source…

Astrophysics · Physics 2016-08-30 Andrew Gould

With several detections, the technique of gravitational microlensing has proven useful for studying planets that orbit stars at Galactic distances, and it can even be applied to detect planets in neighbouring galaxies. So far, planet…

Astrophysics · Physics 2010-11-02 S. Rahvar , M. Dominik

We present the first systematic search for microlensing events with variability in their baselines using data from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III). A total of 137 candidates (88 new) was discovered…

We present the analysis of the microlensing event KMT-2018-BLG-1743. The light curve of the event, with a peak magnification $A_{\rm peak}\sim 800$, exhibits two anomaly features, one around the peak and the other on the falling side of the…

We present a catalog of 450 high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields and, as expected, they show clear concentration toward the…

Microlensing can provide an important tool to study binaries, especially those composed of faint or dark objects. However, accurate analysis of binary-lens light curves is often hampered by the well-known degeneracy between close (s<1) and…

We study light variability of gravitationally magnified high-redshift star clusters induced by a foreground population of microlenses. This arises as the incoherent superposition of light variations from a large number of source stars…

Astrophysics of Galaxies · Physics 2021-01-13 Liang Dai

For microlenses with sufficiently low mass, the angular radius of the source star can be much larger than the angular Einstein ring radius of the lens. For such extreme finite source effect (EFSE) events, finite source effects dominate…

High Energy Astrophysical Phenomena · Physics 2022-03-14 Samson A. Johnson , Matthew T. Penny , B. Scott Gaudi

The position of the giant elliptical galaxy M87 at the center of the Virgo Cluster means that the inferred column density of dark matter associated with both the cluster halo and the galaxy halo is quite large. This system is thus an…

Automatic classification of variability is now possible with tools like neural networks. Here, we present two neural networks for the identification of microlensing events -- the first discriminates against variable stars and the second…

Astrophysics · Physics 2009-11-10 V. Belokurov , N. W. Evans , Y. Le Du

Real-time detection of microlensing has moved from proof of concept in 1994 to a steady stream of events this year. Global dissemination of these events by the MACHO and OGLE collaborations has made possible intensive photometric and…

First proposed by Paczynski in 1986, microlensing has been instrumental in the search of compact dark matter as well as discovery and characterization of exoplanets. In this article, we provide a brief history of microlensing, especially on…

Instrumentation and Methods for Astrophysics · Physics 2017-11-16 Chien-Hsiu Lee

A comprehensive new approach is presented for deriving probability densities of physical properties characterizing lens or source that constitute an observed galactic microlensing event. While previously encountered problems are overcome,…

Astrophysics · Physics 2009-11-11 M. Dominik

We combine Spitzer and ground-based observations to measure the microlens parallax of OGLE-2005-SMC-001, the first such space-based determination since S. Refsdal proposed the idea in 1966. The parallax measurement yields a projected…

Despite the detection of a large number of gravitational microlensing events, the nature of Galactic dark matter remains very uncertain. This uncertainty is due to two major reasons: the lens parameter degeneracy in the measured Einstein…

Astrophysics · Physics 2009-10-31 Cheongho Han , Tu-Whan Kim

A major problem in the interpretation of microlensing events is that the only measured quantity, the Einstein time scale t_E, is a degenerate combination of the three quantities one would like to know, the mass, distance, and speed of the…

Astrophysics · Physics 2009-10-31 Andrew Gould , Nikolay Andronov