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In recent years various models for the Galactic distribution of massive compact halo objects (MACHOs) have been proposed for the interpretation of microlensing toward the Large Magellanic Cloud (LMC). A direct way to fit the best model is…

Astrophysics · Physics 2009-11-10 Sohrab Rahvar , Sima Ghassemi

We present the results from the OGLE-II survey (1996-2000) towards the Large Magellanic Cloud (LMC), which has the aim of detecting the microlensing phenomena caused by dark matter compact objects in the Galactic Halo (Machos). We use high…

After a decade of gravitational microlensing experiments, 13 to 17 events by MACHO (depending on quality) and two events by EROS have been detected. All of those have been observed in the direction of Large Magellanic Cloud. We use Evans…

Astrophysics · Physics 2009-11-07 Sohrab Rahvar

Although point caustics harbour a larger potential for measuring the brightness profile of stars during the course of a microlensing event than (line-shaped) fold caustics, the effect of lens binarity significantly limits the achievable…

Astrophysics · Physics 2009-11-10 M. Dominik

We present the observations of the binary lensing event MACHO-98-SMC-1 conducted at the Mt.~Stromlo 74" telescope by the Microlensing Planet Search (MPS) collaboration. The MPS data constrain the first caustic crossing to have occurred…

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

MACHO-97-BLG-41 is a gravitational microlensing event produced by a lens composed of multiple masses detected by the first-generation lensing experiment. For the event, there exist two different interpretations of the lens from independent…

Solar and Stellar Astrophysics · Physics 2015-06-15 Youn Kil Jung , Cheongho Han , Andrew Gould , Dan Maoz

The first micro-lensing event discovered towards the Small Magellanic Cloud by the MACHO collaboration (Alcock et al. 1997b) had a very long time scale, t_0 = 123 days. The EROS collaboration (Palanque-Delabrouille et al. 1997) discovered a…

Astrophysics · Physics 2007-05-23 Bohdan Paczynski

We calculate the optical depth and the number of events due to gravitational microlensing towards the Galactic bulge, the spiral arm directions $\gamma$ Scutum, $\beta$ Scutum, $\gamma$ Normae, $\vartheta$ Muscae and some dwarf galaxies in…

Astrophysics · Physics 2007-05-23 Lukas Grenacher , Philippe Jetzer , Marcus Strässle , Francesco De Paolis

Massive Compact objects in the halo, known as MACHOs, have been postulated as the origin of a substantial fraction of `dark matter' known to exist in the haloes of galaxies$^{1,2}$. Paczy\'nski$^3$ has suggested that it might possible to…

Astrophysics · Physics 2015-06-24 Kailash C. Sahu

The rotation of the disk of the Large Magellanic Cloud (LMC) is derived from the radial velocities of 422 carbon stars. New aspects of this analysis include the propagation of uncertainties in the LMC proper motion with a Monte Carlo, and a…

Astrophysics · Physics 2014-10-13 David R. Alves , Cailin A. Nelson

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 report the result of the analysis of the light curve of a caustic-crossing binary-lens microlensing event OGLE-2009-BLG-023/MOA-2009-BLG-028. Even though the event was observed solely by survey experiments, we could uniquely determine…

Gravitational lensing events provide unique opportunities to discover and study planetary systems and binaries. Here we build on previous work to explore the role that orbital motion can play in both identifying and learning more about…

Earth and Planetary Astrophysics · Physics 2014-12-25 Rosanne Di Stefano , Ann Esin

Recent determination of the outer rotation curve of the Galaxy suggests that the total Galactic mass is likely to concentrate into a region of radius $\sim2R_0$. If this finding is correct, the previously estimated optical depth of…

Astrophysics · Physics 2016-08-30 Zong-Hong Zhu , Xiang-Ping Wu

Despite the suspected binarity for a significant fraction of Galactic lenses, the current photometric surveys detected binary microlensing events only for a small fraction of the total events. The detection efficiency is especially low for…

Astrophysics · Physics 2009-10-31 Cheongho Han

Gravitational microlensing offers a powerful method with which to probe a variety of binary-lens systems, as the binarity of the lens introduces deviations from the typical (single-lens) Paczy\'nski behaviour in the event light curves.…

Solar and Stellar Astrophysics · Physics 2015-06-18 A. A. Nucita , M. Giordano , F. De Paolis , G. Ingrosso

We present the analysis of a binary microlensing event KMT-2016-BLG-2052, for which the lensing-induced brightening of the source star lasted for 2 seasons. We determine the lens mass from the combined measurements of the microlens parallax…

The two outer triangular caustics (regions of infinite magnification) of a close binary microlens move much faster than the components of the binary themselves, and can even exceed the speed of light. When $\epsilon > 1$, where $\epsilon c$…

Astrophysics · Physics 2009-10-31 Zheng Zheng , Andrew Gould

I present a new analysis of the MACHO Project 5.7 year Large Magellanic Cloud (LMC) microlensing data set that incorporates the effects of contamination of the microlensing event sample by variable stars. Photometric monitoring of MACHO LMC…

Astrophysics · Physics 2009-11-10 David P. Bennett