Related papers: The inverse problem in microlensing: from the opti…
A particular open problem in cosmology is whether dark matter on small scales is clumpy, forming gravitationally-bound halos distributed within the Galaxy. The practical difficulties inherent in testing this hypothesis stem from the fact…
After decades of searching, the true nature of dark matter still eludes us. One potential probe of the form of dark matter in galaxy clusters is to search for microlensing variability in the giant arcs and arclets. In this paper, a simple…
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…
We investigate the effects of numerous dark matter subhalos in a galaxy-sized halo on the events of strong lensing, to assess their presence as expected from the cold dark matter scenario. Lens galaxies are represented by a smooth ellipsoid…
It has been shown by Paczy\'nski that gravitational microlensing is a useful method to detect brown dwarfs in the dark halo of our galaxy. At present several experiments are carried out to monitor several million stars in the Large…
(Short version) The nature and the location of the lenses discovered in the microlensing surveys done so far towards the LMC remain unclear. This contribution is comprised of two distinct parts. In the first part, motivated by these…
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…
We present a maximum-likelihood analysis of galaxy-galaxy lensing effects in galaxy clusters and in the field. The aim is to determine the accuracy and robustness of constraints that can be obtained on galaxy halo properties in both…
We investigate the feasibility of extracting the gravitational nanolensing signal due to the presence of subsolar mass halos within galaxy-sized dark matter halos. We show that subsolar mass halos in a lensing galaxy can cause strong…
The splashback radius ($R_{\rm sp}$) of dark matter halos has recently been detected using weak gravitational lensing and cross-correlations with galaxies. However, different methods have been used to measure $R_{\rm sp}$ and to assess the…
Galaxy-galaxy lensing measures the mean excess surface density DS(r) around a sample of lensing galaxies. We develop a method for combining DS(r) with the galaxy correlation function xi_gg(r) to constrain Omega_m and sigma_8, going beyond…
We study the accuracy of inference of the massive halo objects' (MHO or `Macho') mass function from microlensing events observed toward LMC. Assuming the spatial distribution and kinematics of the objects are known, the slope and the range…
The flux ratios of strongly lensed quasars have previously been used to infer the properties of dark matter. In these analyses it is crucial to separate the effect of the main lensing galaxy and the low-mass dark matter halo population. In…
Microlensing of gravitationally lensed quasars by the stars in the foreground lens galaxy can be used to probe the nature of dark matter, to determine the mean stellar mass in the lens galaxy, and to measure the internal structure of quasar…
Foundations of standard theory of microlensing are described, namely we consider microlensing stars in Galactic bulge, the Magellanic Clouds or other nearby galaxies. We suppose that gravitational microlenses lie between an Earth observer…
Microlensing is one of the most powerful tools for probing the nature of dark halo objects and the sources they lens. As our nearest massive galaxy, M31 provides a rich source population with many potential lenses in its halo crossing our…
Integral measures of weak gravitational lensing by dark-matter haloes, like the aperture mass, are sensitive to different physical halo properties dependent on the halo mass density profile. For isothermal profiles, the relation between…
The longest microlensing events provide enough information to estimate the mass and distance of the lens. Among hundreds of millions of stars which were monitored for many years by the OGLE project we selected those with clear parallax…
The halo shape plays a central role in determining important observational properties of the haloes such as mass, concentration and lensing cross-sections. The triaxiality of lensing galaxy clusters has a substantial impact on the…
The MACHO Project is searching for galactic dark matter in the form of massive compact halo objects (Machos). Millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge are photometrically…