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We describe a real-time spectroscopic program to observe bright gravitational microlensing events toward the Galactic Bulge. The program is carried out using the NTT at ESO. We present the preliminary analysis of the microlensing events we…

Astrophysics · Physics 2007-05-23 D. Lennon , S. Mao , J. Reetz , T. Gehren , L. Yan , A. Renzini

The mass-sheet degeneracy is a well-known problem in gravitational lensing which limits our capability to infer astrophysical lens properties or cosmological parameters from observations. As the number of gravitational wave observations…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-07 Paolo Cremonese , Jose María Ezquiaga , Vincenzo Salzano

The Einstein time scale, which is the only information obtained from current microlensing experiments, results from a complicated combination of the lens parameters that we want to determine. Of the methods for breaking the lens parameter…

Astrophysics · Physics 2007-05-23 Cheongho Han

We analyze the very short Einstein timescale ($t_\rm E \simeq 7\,{\rm hr}$) event KMT-2019-BLG-2073. Making use of the pronounced finite-source effects generated by the clump-giant source, we measure the Einstein radius $\theta_\rm E \simeq…

Gravitational microlensing is a powerful method for detecting and characterizing free-floating planetary-mass objects (FFPs). FFPs could have exomoons rotating them. In this work, we study the probability of realizing these systems (i.e.,…

Earth and Planetary Astrophysics · Physics 2023-02-22 Sedighe Sajadian , Parisa Sangtarash

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

Currently, 6 candidate binary lens events have been reported, while only a single candidate binary source event has been reported. To account for the rarity of binary source events, Dominik pointed out that for a typical binary source event…

Astrophysics · Physics 2009-10-30 Cheongho Han , Youngjin Jeong

Interferometers offer multiple methods for studying microlensing events and determining the properties of the lenses. We investigate the study of microlensing events with optical interferometers, focusing on narrow-angle astrometry,…

Astrophysics · Physics 2009-11-07 Neal Dalal , Benjamin F. Lane

The phenomenon of microlensing has successfully been used to detect extrasolar planets. By observing characteristic, rare deviations in the gravitational microlensing light curve one can discover that a lens is a star--planet system. In…

Earth and Planetary Astrophysics · Physics 2014-04-15 Krzysztof Rybicki , Łukasz Wyrzykowski

In extreme scattering events, the brightness of a compact radio source drops significantly, as light is refracted out of the line of sight by foreground plasma lenses. Despite recent efforts, the nature of these lenses has remained a…

High Energy Astrophysical Phenomena · Physics 2023-06-28 Hengrui Zhu , Daniel Baker , Ue-Li Pen , Dan R. Stinebring , Marten H. van Kerkwijk

Microlensing events are now regularly being detected by monitoring the flux of a large number of potential sources and measuring the combined magnification of the images. This phenomenon could also be detected directly from the…

Astrophysics · Physics 2009-10-28 Jordi Miralda-Escude

We attempt to identify all microlensing parallax events for which the parallax fit improves \Delta\chi^2 > 100 relative to a standard microlensing model. We outline a procedure to identify three types of discrete degeneracies (including a…

The effect of stars on the lensing properties of the supermassive black hole in the Galactic Center is similar to the effect of planets on microlensing by a star. We show that the dense stellar cluster around SgrA* increases by factors of a…

Astrophysics · Physics 2009-10-31 Tal Alexander , Abraham Loeb

Microlensing event OGLE-2002-BLG-055 is characterized by a smooth, slightly asymmetric single-lens curve with an isolated, secure data point that is ~0.6 magnitudes brighter than neighboring points separated by a few days. It was previously…

Astrophysics · Physics 2008-11-26 B. Scott Gaudi , Cheongho Han

In recent years, gravitational lensing has been used as a means to detect substructure in galaxy-sized halos, via anomalous flux ratios in quadruply-imaged lenses. In addition to causing anomalous flux ratios, substructure may also perturb…

Astrophysics · Physics 2011-02-11 Jacqueline Chen , Eduardo Rozo , Neal Dalal , James E. Taylor

Gravitational microlensing surveys target very dense stellar fields in the local group. As a consequence the microlensed source stars are often blended with nearby unresolved stars. The presence of `blending' is a cause of major uncertainty…

Astrophysics · Physics 2009-11-13 Martin C. Smith , Przemyslaw Wozniak , Shude Mao , Takahiro Sumi

We study the influence of general lens and source velocities on the gravitational deflection of light by single and two-point-mass microlenses with general axis orientation. We demonstrate that in all cases the lens equation preserves its…

Astrophysics · Physics 2009-11-10 David Heyrovsky

Microlensing events provide a unique capacity to study the stellar remnant population of the Galaxy. Optical microlensing suffers from a near complete degeneracy between the mass, the velocity and the distance. However, a subpopulation of…

High Energy Astrophysical Phenomena · Physics 2017-01-12 M. Karami , A. E. Broderick , S. Rahvar , M. Reid