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It is shown that a significant amount of detectable gravitational microlensing events that could potentially be found by MAssively Parallel Photometry (MAPP) projects (such as the MACHO, EROS and OGLE collaborations) will occur for stars…

Astrophysics · Physics 2009-10-22 Robert J. Nemiroff

We describe observations carried out by the MOA group of the Galactic Bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These…

Recently the Polish-American collaboration OGLE has reported the observation of four possible microlensing events by monitoring, over several months, the brightness of millions of stars in the region of the galactic bulge. If these events…

Astrophysics · Physics 2009-10-22 Ph. Jetzer

In the framework of microlensing searches towards the Large Magellanic Cloud (LMC), we discuss the results presented by the OGLE collaboration for their OGLE-II campaign \citep{lukas09}. We evaluate the optical depth, the duration and the…

Astrophysics of Galaxies · Physics 2015-05-14 S. Calchi Novati , L. Mancini , G. Scarpetta , L. Wyrzykowski

Microlensing has a unique advantage for detecting dark objects in the Milky Way, such as free-floating planets, neutron stars, and stellar-mass black holes. Most microlensing surveys focus on the Galactic bulge, where higher stellar density…

Astrophysics of Galaxies · Physics 2024-11-11 Ruocheng Zhai , Antonio C. Rodriguez , Shude Mao , Casey Y. Lam , Eric C. Bellm , Josiah Purdum , Frank J. Masci , Avery Wold

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

It has been shown by Paczy\'nski that gravitational microlensing is potentially a useful method for detecting the dark constituents of the halo of our galaxy, if their mass lies in the approximate domain $10^{-6}<M/M_\odot<10^{-1}$.…

Astrophysics · Physics 2008-02-03 Philippe Jetzer

We present results from a search for gravitational microlensing of stars in the Large Magellanic Cloud by low mass objects in the Galactic Halo. The search uses the CCD light curves of about 82,000 stars with up to 46 measurements per night…

Microlensing maps -- that is, contours of equal numbers of events per $10^6$ source stars -- are provided for the inner Galaxy under two alternative hypotheses : (1) the bulge is an oblate axisymmetric spheroid or (2) the bulge is a prolate…

Astrophysics · Physics 2009-10-22 N. W. Evans

We present the first M31 candidate microlensing events from the Microlensing Exploration of the Galaxy and Andromeda (MEGA) survey. MEGA uses several telescopes to detect microlensing towards the nearby Andromeda galaxy, M31, in order to…

Lunar occultation can be used to measure the proper motions of some of the long time scale microlensing events, $t_{e} \gsim 70$ days, now being detected toward the Galactic bulge. The long events are difficult to explain within the context…

Astrophysics · Physics 2009-10-28 Cheongho Han , Vijay K. Narayanan , Andrew Gould

Microlensing is a powerful technique to study the Galactic population of "dark" objects such as exoplanets both bound and unbound, brown dwarfs, low-luminosity stars, old white dwarfs, neutron stars, and almost the only way to study…

The dependence of microlensing time scale frequency distributions and optical depth toward the galactic center on galactic model parameters is explored in detail for a distribution of stars consisting of the Zhao (1996) bar and nucleus and…

Astrophysics · Physics 2009-10-30 S. J. Peale

The EROS-2 collaboration has conducted a survey of the Magellanic Clouds between July 1996 and February 2003 (6.7 years), in order to search for microlensing phenomena due to putative machos (massive astronomical compact halo objects).…

Astrophysics · Physics 2007-05-23 Patrick Tisserand , Alain Milsztajn

We present results of a microlensing survey toward the Andromeda Galaxy (M31) carried out during four observing seasons at the Isaac Newton Telescope (INT). This survey is part of the larger microlensing survey toward M31 performed by the…

It has been proposed that the Galaxy might contain a population of cold clouds in numbers sufficient to account for a substantial fraction of the total mass of the Galaxy. These clouds would have masses of the order of 10^{-3} Solar mass…

Astrophysics · Physics 2009-10-31 Roman R. Rafikov , Bruce T. Draine

The measurements of the possible gravitational microlensing events are analysed with a simple yet accurate disc--halo model of the Milky Way Galaxy. This comprises a luminous exponential disc embedded in a flattened dark matter halo with…

Astrophysics · Physics 2016-06-08 N. W. Evans , J. Jijina

We propose to search for MACHOs by observing EAGLE (Extremely Amplified Gravitational LEnsing) events of a majority of dim stars. This search is independent of the usual one. For the detection limit of EAGLE (about 20 mag), about 100 f…

Astrophysics · Physics 2009-10-30 Takashi Nakamura , Ryoichi Nishi

We perform an analytical study and a Monte Carlo (MC) analysis of the main features for microlensing events in pixel lensing observations towards M31. Our main aim is to investigate the lens nature and location of the 14 candidate events…

Astrophysics · Physics 2009-11-13 G. Ingrosso , S. Calchi-Novati , F. De Paolis , Ph. Jetzer , A. A. Nucita , F. Strafella

We describe the discovery of the longest microlensing event ever observed, OGLE-1999-BUL-32, also independently identified by the MACHO collaboration as MACHO-99-BLG-22. This unique event has an Einstein radius crossing time of 641 days.…