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Numerical simulations and theoretical studies of the gravitational microlensing effect of a population of small bodies distributed along the line of sight to a compact light source such as a quasar indicate that caustic crossing effects…

Astrophysics · Physics 2007-05-23 M. R. S. Hawkins

A long standing question in cosmology is whether gravitational lensing changes the distance-redshift relation $D(z)$ or the mean flux density of sources. Interest in this has been rekindled by recent studies in non-linear relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-16 Nick Kaiser , John A. Peacock

In a microlensing event, a large magnification occurs at caustic crossing and provides an opportunity to obtain a stronger signal associated with the object. In this paper we study the possibility of magnetic field detection in a…

Solar and Stellar Astrophysics · Physics 2015-08-04 Ahmad Mehrabi , Habib khosroshahi , Hadi Rahmani

Measurements of the microlensing optical depth, tau, towards the Galactic bulge appear to depend on the method used to obtain them. Those values based on the lensing of red clump giants (RCGs) appear to be significantly lower than those…

Astrophysics · Physics 2008-11-26 Alexander Wood

We examine a caustic-straddling arc at $z=0.9397$ in the field of the galaxy cluster MACS J0416.1-2403 ($z=0.397$) using archival multiband HST images and show that its surface brightness exhibits anomalies that can be explained by a single…

Astrophysics of Galaxies · Physics 2019-07-31 Alexander A. Kaurov , Liang Dai , Tejaswi Venumadhav , Jordi Miralda-Escudé , Brenda Frye

The microlensing probability (optical depth $\tau$) toward the Galactic center carries information about the mass distribution of the Galactic bulge/bar, so can be used to constrain the very uncertain shape parameters of the bar. We find…

Astrophysics · Physics 2015-06-24 HongSheng Zhao , Shude Mao

We present the analysis of the light curves of 8.5 million stars observed during two seasons by EROS (Experience de Recherche d'Objets Sombres), in the galactic plane away from the bulge. Three stars have been found that exhibit luminosity…

Astrophysics · Physics 2008-11-26 F. Derue , C. Afonso , C. Alard , J-N. Albert

Gravitational microlensing with binary lensing is one of the channels for detecting exoplanets. Due to the degeneracy of the lens parameters for the binary microlensing, additional features such as parallax and finite-size effects need to…

Earth and Planetary Astrophysics · Physics 2024-08-15 Samaneh Sarbaz , Sohrab Rahvar

The angular cross-correlation between two galaxy samples separated in redshift is shown to be a useful measure of weak lensing by large-scale structure. Angular correlations in faint galaxies arise due to spatial clustering of the galaxies…

Astrophysics · Physics 2020-11-25 R. Moessner , Bhuvnesh Jain

The dependence of microlensing time scale frequency distributions and optical depth toward the galactic center on galactic model parameters is explored in detail for a distribution of stars consisting of the Zhao (1996) bar and nucleus and…

Astrophysics · Physics 2009-10-30 S. J. Peale

The magnifications of compact-source lenses are extremely sensitive to the presence of low mass dark matter halos along the entire sight line from the source to the observer. Traditionally, the study of dark matter structure in…

The current methods available to estimate gravitational shear from astronomical images of galaxies introduce systematic errors which can affect the accuracy of weak lensing cosmological constraints. We study the impact of KSB shape…

Strong lensing is one of the most direct probes of the mass distribution in the inner regions of galaxy clusters. It can be used to constrain the density profiles and to measure the mass of the lenses. Moreover, the abundance of strong…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Massimo Meneghetti , Cosimo Fedeli , Francesco Pace , Stefan Gottloeber , Gustavo Yepes

Gravitational microlensing of planetary-mass objects (or "nanolensing", as it has been termed) can be used to probe the distribution of mass in a galaxy that is acting as a gravitational lens. Microlensing and nanolensing light curve…

Astrophysics of Galaxies · Physics 2015-06-03 H. Garsden , N. F. Bate , G. F. Lewis

With the increase in the number of observed gravitational wave (GW) signals, detecting strongly lensed GWs by galaxies has become a real possibility. Lens galaxies also contain microlenses (e.g., stars and black holes), introducing further…

Astrophysics of Galaxies · Physics 2022-10-05 Ashish Kumar Meena , Anuj Mishra , Anupreeta More , Sukanta Bose , Jasjeet Singh Bagla

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…

Astrophysics of Galaxies · Physics 2023-10-11 Tristan Blaineau , Marc Moniez

The correlation between source galaxies and lensing potentials causes a systematic effect on measurements of cosmic shear statistics, known as the source-lens clustering (SLC) effect. The SLC effect on the skewness of lensing convergence,…

Chromaticity effects introduced by the finite source size in microlensing events by presumed natural wormholes are studied. It is shown that these effects provide a specific signature that allow to discriminate between ordinary and negative…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Ernesto Eiroa , Gustavo E. Romero , Diego F. Torres

EROS has searched for microlensing toward four directions in the Galactic plane away from the Galactic center. The interpretation of the catalog optical depth is complicated by the spread of the source distance distribution. We compare the…

Astrophysics of Galaxies · Physics 2017-08-30 Marc Moniez , Sedighe Sajadian , Mansour Karami , Sohrab Rahvar , Reza Ansari