Related papers: Gravitational Microlensing and the Galactic Halo
We study the gravitational lensing properties of a massive object in a dark matter halo, concentrating on the critical curves and caustics of the combined lens. We model the system in the simplest approximation by a point mass embedded in a…
Recently obtained kinematic data has shown that the Large Magellanic Cloud (LMC) possesses an old stellar halo. In order to further characterize the properties of this halo, parametric King models are fit to the surface density of RR Lyrae…
We carry out a systematic investigation of the total mass density profile of massive (Mstar>2e11 Msun) early-type galaxies and its dependence on galactic properties and host halo mass with the aid of a variety of lensing/dynamical data and…
One of the possible astrophysical solutions to the galactic dark matter problem is the presence of a significant amount of ``dark'' compact objects (MACHOs) in galactic dark matter halos. MEGA (Microlensing Exploration of the Galaxy and…
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…
Gravitational microlensing is a robust tool to detect and directly measure the abundance and mass of any kind of compact objects, either in our galaxy or in the extragalatic domain. On basis to generic, broadly applicable arguments, it is…
The statistics of wide-separation (6'' < theta < 15'') gravitational lenses constrain the amount of mass in the cores of dark matter halos on group and cluster mass scales. For a family of halo models with a central cusp $\rho \propto…
Increasing evidences suggest that the Galactic halo is lumpy on kpc scales due to the accretion of at least a dozen small galaxies (LMC/SMC, Sgr, Fornax etc.). Faint stars in such lumpy structures can significant microlense a background…
We use the calculations derived in a previous paper (M\'era, Chabrier and Schaeffer, 1997), based on observational constraints arising from star counts, microlensing experiments and kinematic properties, to determine the amount of dark…
We use a series of high-resolution simulations of a `Milky-Way' halo coupled to semi-analytic methods to study the formation of our own Galaxy and of its stellar halo. The physical properties of our model Milky Way, as well as the age and…
We consider the contribution of neutron stars and black holes to the dynamical mass of galactic halos. In particular, we show that if these compact objects were produced by an early generation of stars with initial metallicity less than…
We have searched for long duration microlensing events originating from intermediate mass Black Holes (BH) in the halo of the Milky Way, using archival data from EROS-2 and MACHO photometric surveys towards the Large Magellanic Cloud. We…
Many high velocity HI clouds (HVCs) are now believed to be scattered throughout the Galactic halo on scales of tens of kiloparsecs. Some of these clouds appear to contain substantial HI masses (>10^6 Msun). It has been suggested that these…
According to the now strongly supported concordance $\Lambda$CDM model, galaxies may be grossly described as a luminous component embedded in a dark matter halo. The density profile of these mass dominating haloes may be determined by N -…
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…
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…
Cosmological simulations predict that galaxies are embedded into triaxial dark matter haloes, which appear approximately elliptical in projection. Weak gravitational lensing allows us to constrain these halo shapes and thereby test the…
We present the results of a study of the average mass profile around galaxies using weak gravitational lensing. We use 45.5 deg^2 of R_C band imaging data from the Red-Sequence Cluster Survey (RCS) and define a sample of 1.2\times 10^5…
Measuring the distribution of mass on galaxy cluster scales is a crucial test of the Lambda CDM model, providing constraints on the nature of dark matter. Recent work investigating mass distributions of individual galaxy clusters using…
If the density distribution \rho (r) of MACHOs is spherically symmetric with respect to the Galactic center, it is shown that the minimal total mass M_{min}^{{ MACHO}} of the MACHOs is 1.7\times 10^{10}\sol \tau_{-6.7}^{{ LMC}} where…