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We present measurements of the microlensing optical depth and event rate toward the Galactic Bulge based on two years of the MOA-II survey. This sample contains ~1000 microlensing events, with an Einstein Radius crossing time of t_E < 200…

We present the PLANET photometric data set for \ob14, a high magnification ($A_{\rm max}\sim 16$) event alerted by the OGLE collaboration toward the Galactic bulge in 1998. The PLANET data set consists a total of 461 I-band and 139 $V-$band…

The discoveries of 17 microlensing event candidates have been reported over the last year by three teams conducting unprecedented mass photometric searches in the direction of the Galactic bulge and the Magellanic Clouds. These include 10…

Astrophysics · Physics 2009-09-25 A. Udalski , M. Szymanski , J. Kaluzny , M. Kubiak , M. Mateo , W. Krzeminski , B. Paczynski

Microlensing planets occurring on faint source stars can escape detection due to their weak signals. Occasionally, detections of such planets are not reported due to the difficulty of extracting high-profile scientific issues on the…

Microlensing observations have now become a useful tool in searching for non--luminous astrophysical compact objects (brown dwarfs, faint stars, neutron stars, black holes and even planets). Originally conceived for establishing whether the…

Astrophysics · Physics 2016-08-30 E. Roulet , S. Mollerach

While dozens of stellar mass black holes have been discovered in binary systems, isolated black holes have eluded detection. Their presence can be inferred when they lens light from a background star. We attempt to detect the astrometric…

Solar and Stellar Astrophysics · Physics 2016-10-19 J. R. Lu , E. Sinukoff , E. O. Ofek , A. Udalski , S. Kozlowski

Microlensing campaigns have a long history of observations covering the Galactic bulge, where thousands of detections have been obtained, including many exoplanetary systems. The Euclid Galactic Bulge Survey represents a unique opportunity…

We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-source effects, and the microlens parallaxes are derived from…

Solar and Stellar Astrophysics · Physics 2020-03-04 Weicheng Zang , Yossi Shvartzvald , Tianshu Wang , Andrzej Udalski , Chung-Uk Lee , Takahiro Sumi , Jesper Skottfelt , Shun-Sheng Li , Shude Mao , Wei Zhu , Jennifer C. Yee , Sebastiano Calchi Novati , Charles A. Beichman , Geoffery Bryden , Sean Carey , B. Scott Gaudi , Calen B. Henderson , Przemek Mróz , Jan Skowron , Radoslaw Poleski , Michał K. Szymański , Igor Soszyński , Paweł Pietrukowicz , Szymon Kozłowski , Krzysztof Ulaczyk , Krzysztof A. Rybicki , Patryk Iwanek , Etienne Bachelet , Grant Christie , Jonathan Green , Steve Hennerley , Dan Maoz , Tim Natusch , Richard W. Pogge , Rachel A. Street , Yiannis Tsapras , Michael D. Albrow , Sun-Ju Chung , Andrew Gould , Cheongho Han , Kyu-Ha Hwang , Youn Kil Jung , Yoon-Hyun Ryu , In-Gu Shin , Sang-Mok Cha , Dong-Jin Kim , Hyoun-Woo Kim , Seung-Lee Kim , Dong-Joo Lee , Yongseok Lee , Byeong-Gon Park , Richard W. Pogge , Ian A. Bond , Fumio be , Richard Barry , David P. Bennett , Aparna Bhattacharya , Martin Donachie , Akihiko Fukui , Yuki Hirao , Yoshitaka Itow , Iona Kondo , Naoki Koshimoto , Man Cheung Alex Li , Yutaka Matsubara , Yasushi Muraki , Shota Miyazaki , Masayuki Nagakane , Clément Ranc , Nicholas J. Rattenbury , Haruno Suematsu , Denis J. Sullivan , Daisuke Suzuki , Paul J. Tristram , Atsunori Yonehara , Martin Dominik , Markus Hundertmark , Uffe G. Jørgensen , Sohrab Rahvar , Sedighe Sajadian , Colin Snodgrass , Valerio Bozza , Martin J. Burgdorf , Daniel F. Evans , Roberto Figuera Jaimes , Yuri I. Fujii , Luigi Mancini , Penelope Longa-Peña , hristiane Helling , Nuno Peixinho , Markus Rabus , John Southworth , Eduardo Unda-Sanzana , Carolina von Essen

A self-consistent stellar dynamical model for the Galactic bar is constructed from about 500 numerically computed orbits with an extension of the Schwarzschild technique. The model fits the {\sl COBE} found asymmetric boxy light…

Astrophysics · Physics 2007-05-23 HongSheng Zhao

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

All current Bulge-Disk models for the inner Galaxy fall short of reproducing self-consistently the observed micro-lensing optical depth by a factor of two ($> 2\sigma$). We show that the least mass-consuming way to increase the optical…

Astrophysics · Physics 2016-08-30 M. Sevenster , A. Kalnajs

OGLE and other projects are likely to discover first stellar mass black holes and the first planets through gravitational lensing in the next year or two. It is important to have follow-up projects ready, using diverse observing methods.…

Astrophysics · Physics 2007-05-23 Bohdan Paczynski

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…

We use the timescale distribution of ~3000 microlensing events measured by the OGLE-III survey, together with accurate new made-to-measure dynamical models of the Galactic bulge/bar region, to measure the IMF in the inner Milky Way. The…

Astrophysics of Galaxies · Physics 2017-07-26 Christopher Wegg , Ortwin Gerhard , Matthieu Portail

During the months when the galactic bulge is visible from the southern hemisphere, there are typically about 8 to 10 on-going microlensing events at any given time. If the lensing stars have planets around them, then the signature of the…

Astrophysics · Physics 2007-05-23 Kailash C. Sahu

Because we know little about the Galactic force-field away from the plane, the Galactic mass distribution is very ill-determined. I show that a microlensing survey of galaxies closer than 50 Mpc would enable us to map in three dimensions…

Astrophysics · Physics 2007-05-23 James Binney

High-cadence observations of the Galactic bulge by the microlensing surveys led to the discovery of a handful of extremely short-timescale microlensing events that can be attributed to free-floating or wide-orbit planets. Here, we report…

The Milky Way has a barred bulge. This article summarizes the current understanding of the main structural parameters and pattern speed of the bar, and compares predicted values for the microlensing optical depth with the bulge microlensing…

Astrophysics · Physics 2008-11-26 Ortwin Gerhard

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 both the technical overview and main science drivers of the fourth phase of the Optical Gravitational Lensing Experiment (hereafter OGLE-IV). OGLE-IV is currently one of the largest sky variability surveys worldwide, targeting…

Solar and Stellar Astrophysics · Physics 2015-04-24 A. Udalski , M. K. Szymański , G. Szymański
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