Related papers: Microlensing in globular clusters: the first confi…
EROS (Exp\'erience de Recherche d'Objets Sombres) has been monitoring the luminosity of 4 million stars in the Large Magellanic Cloud in order to search for gravitational microlensing by unseen objects in the galactic halo. We present here…
The discovery of the Sgr dwarf galaxy (Ibata, Gilmore, Irwin 1994) shows that the Galactic halo contains large clumps which are not full viralized. Stars in such a clump can lense a background extragalactic source. I use parameters of Sgr…
Gravitational microlensing occurs when a foreground star happens to pass very close to our line of sight to a more distant background star. The foreground star acts as a lens, splitting the light from the source star into two images, which…
We analyze the seldomly discussed lensing effects expected in low-z clusters (z = 0.05-0.15), using as an example the bright arc (z=0.073) discovered by Campusano and Hardy(1996) near the dominant cD galaxy of the cluster Abell 3408…
Some previous studies have suggested that massive and intermediate-mass primordial black holes (PBHs) could comprise a substantial fraction of dark matter in the Universe. Such black holes, if they existed in the Milky Way halo, would give…
Microlensing surveys search for the transient brightening of a background star that is the signature of gravitational lensing by a foreground compact object. This technique is an elegant way to search for astrophysical candidates that might…
We investigate gravitational microlensing of point-like lenses surrounded by diffuse gas clouds. Besides gravitational bending, one must also consider refraction and absorption phenomena. According to the cloud density, the light curves may…
We present the details of the Bayesian analysis on the planetary microlensing event MOA-2016-BLG-227, whose excess flux is likely due to a source/lens companion or an unrelated ambient star, as well as of the assumed prior distributions.…
We present a new method to identify and probe planetary companions of stars in the Galactic Bulge and Magellanic Clouds using gravitational microlensing. While spectroscopic studies of these planets is well beyond current observational…
Studies of gravitational microlensing effects require the estimation of their detection efficiency as soon as one wants to quantify the massive compact objects along the line of sight of source targets. This is particularly important for…
In this fourth part of the series presenting the Optical Gravitational Lensing Experiment (OGLE) microlensing studies of the dark matter halo compact objects (MACHOs) we describe results of the OGLE-III monitoring of the Small Magellanic…
We investigated microlensing events detected by the OGLE and KMTNet surveys during the 2024 observing season, focusing on those that exhibit very complex anomaly features. Through this analysis, we found that the light curves of three…
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…
We report the discovery and the analysis of the short timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low mass host, around the brown dwarf/planetary mass boundary, or a…
We investigate properties of Galactic microlensing events in which a stellar object is lensed by a neutron star. For an all-sky photometric microlensing survey, we determine the number of lensing events caused by $\sim10^{5}$…
We present microlens parallax measurements for 21 (apparently) isolated lenses observed toward the Galactic bulge that were imaged simultaneously from Earth and Spitzer, which was ~1 AU West of Earth in projection. We combine these…
One possibility for detecting low-amplitude pulsational variations is through gravitational microlensing. During a microlensing event, the temporary brightness increase leads to improvement in the signal-to-noise ratio, and thereby better…
The MACHO project has been monitoring about ten million stars in the Large Magellanic Cloud in the search for gravitational microlensing events caused by massive compact halo objects (Machos) in the halo of the Milky Way. In our standard…
Gravitational lensing is an important tool for probing the mass distribution of galaxies. In this letter we report the discovery of a new quadruple lens HST 1411+5211 found in archived WFPC2 images of the galaxy cluster CL140933+5226. If…
Once only accessible in nearby galaxies, we can now study individual stars across much of the observable universe aided by galaxy-cluster gravitational lenses. When a star, compact object, or multiple such objects in the foreground…