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We review recent gravitational microlensing results from the EROS, MACHO, and OGLE collaborations, and present some details of the very latest MACHO results toward the Galactic Bulge. The MACHO collaboration has now discovered in excess of…

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…

A Massive Compact Halo Object (Macho) that lenses a background star will magnify different parts of the rotating stellar disk by varying amounts. The differential magnification will cause a shift in the centroid of the star's spectral lines…

Astrophysics · Physics 2009-10-22 Dan Maoz , Andrew Gould

We present photometric observations and analysis of the second microlensing event detected towards the Small Magellanic Cloud (SMC), MACHO Alert 98-SMC-1. This event was detected early enough to allow intensive observation of the…

We present previously unpublished photometry of three Large Magellanic Cloud (LMC) microlensing events and show that the new photometry confirms the microlensing interpretation of these events. These events were discovered by the MACHO…

Astrophysics · Physics 2009-11-10 David P. Bennett , Andrew C. Becker , Austin Tomaney

Caustic crossing microlensing events provide us a unique opportunity to measure the relative proper motion of the lens to the source, and so those caused by binary MACHOs are of great importance for understanding the structure of the…

Astrophysics · Physics 2009-10-31 Mareki Honma

The primary goal of this paper is to provide the evidence that can either prove or falsify the hypothesis that dark matter in the Galactic halo can clump into stellar-mass compact objects. If such objects existed, they would act as lenses…

The simplest interpretation of the microlensing events observed towards the Large Magellanic Clouds is that approximately half of the mass of the Milky Way halo is in the form of MAssive Compact Halo Objects with $M \sim 0.5 M_{\odot}$. It…

Astrophysics · Physics 2009-10-31 Anne M Green

Following previous suggestions of other researchers, this paper discusses the prospects for astrometric observation of MACHO gravitational microlensing events. We derive the expected astrometric observables for a simple microlensing event…

Astrophysics · Physics 2009-10-30 A. F. Boden , M. Shao , D. Van Buren

The number and properties of observed gravitational microlensing events depend on the distribution and kinematics of stars and other compact objects along the line of sight. In particular, precise measurements of the microlensing optical…

Recently the French EROS collaboration and the American-Australian MACHO collaboration have reported the observation of altogether three possible microlensing events by monitoring over several years the brightness of millions of stars in…

Astrophysics · Physics 2009-10-22 Philippe Jetzer , Eduard Masso

I demonstrate that one can detect pixel gravitational microlensing events at the rate $\sim 180\ {\rm events}\ {\rm yr}^{-1}$ and that some fraction of events ($\sim 15$) will be good enough to measure time scales at the $20\%$ level if the…

Astrophysics · Physics 2009-10-28 Cheongho Han

MACHO-96-BLG-5 is a microlensing event observed towards the bulge of the Galaxy with exceptionally long duration of $\sim 970$ days. The microlensing parallax fit parameters were used to estimate the lens mass $M=6^{+10}_{-3}$ M$_{\odot}$…

Astrophysics · Physics 2007-05-23 A. A. Nucita , F. De Paolis , G. Ingrosso , D. Elia , J. de Plaa , J. S. Kaastra

Recently, from the Hubble Space Telescope (HST) images of one of the Large Magellanic Cloud (LMC) events taken 6.3 years after the original lensing measurement, Alcock et al. were able to directly image the lens. Although the first resolved…

Astrophysics · Physics 2009-11-07 Cheongho Han , Heon-Young Chang

We present measurements of the microlensing optical depth and event rate toward the Galactic bulge using the dataset from the 2006--2014 MOA-II survey, which covers 22 bulge fields spanning ~42 deg^2 between -5 deg < l < 10 deg and -7 deg <…

Gravitational microlensing events of high magnification provide exceptional sensitivity to the presence of low-mass planets orbiting the lens star, including planets with masses as low as that of Earth. The essential requirement for the…

Astrophysics · Physics 2008-05-14 Philip Yock

Results are presented from the MACHO collaboration gravitational microlensing search. The experiment and the nearly 50 microlensing events that have been detected are described. Limits on the baryonic content of the halo are given, as are…

The EROS microlensing survey has monitored nearly 100 million stars for seven years, to search for halo brown dwarfs and compact objects in the Galactic disk. In this paper, we review the various EROS observation programs and the…

Astrophysics · Physics 2007-05-23 R. Ansari

Foundations of standard theory of microlensing are described, namely we consider microlensing stars in Galactic bulge, the Magellanic Clouds or other nearby galaxies. We suppose that gravitational microlenses lie between an Earth observer…

Astrophysics · Physics 2007-05-23 A. F. Zakharov

An expression is provided for the self-lensing optical depth of the thin LMC disk surrounded by a shroud of stars at larger scale heights. The formula is written in terms of the vertical velocity dispersion of the thin disk population. If…

Astrophysics · Physics 2009-10-31 N. W. Evans , E. J. Kerins