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A substantial part of the dark matter of the Universe could be in the form of compact objects (MACHOs), detectable through gravitational microlensing effects as they pass through the line of sight to background light sources. So far, most…

Astrophysics · Physics 2009-11-13 E. Zackrisson , T. Riehm

We estimate the fraction of mass that is composed of compact objects in gravitational lens galaxies. This study is based on microlensing measurements (obtained from the literature) of a sample of 29 quasar image pairs seen through 20 lens…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 E. Mediavilla , J. A. Munoz , E. Falco , V. Motta , E. Guerras , H. Canovas , C. Jean , A. Oscoz , A. M. Mosquera

Microlensing near macro-caustics is a complex phenomenon in which swarms of micro-images produced by micro-caustics form on both sides of a macro-critical curve. Recent discoveries of highly magnified images of individual stars in massive…

Astrophysics of Galaxies · Physics 2024-04-15 Luke Weisenbach , Timo Anguita , Jordi Miralda-Escudé , Masamune Oguri , Prasenjit Saha , Paul L. Schechter

The probability of detecting a planetary companion of a lensing star during a microlensing event toward the Galactic center, averaged over all relevant event and galactic parameters, when the planet-star mass ratio $q=0.001$ has a maximum…

Astrophysics · Physics 2009-11-06 S. J. Peale

The fraction of quasar's and gamma-ray burst (GRB) afterglows that vary due to microlensing by the stellar populations of intervening elliptical/S0 galaxies is computed by combining the joint distribution of effective microlensing…

Astrophysics · Physics 2009-11-07 J. S. B. Wyithe , E. L. Turner

Recent observations of lensed galaxies at cosmological distances have detected individual stars that are extremely magnified when crossing the caustics of lensing clusters. In idealized cluster lenses with smooth mass distributions, two…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-30 Tejaswi Venumadhav , Liang Dai , Jordi Miralda-Escudé

Quasar microlensing is both a very useful tool in cosmology and astrophysics, and a source of uncertainty in some studies like the determination of the Hubble constant from lensed quasars. Microlensing probability and time-scales have been…

Astrophysics of Galaxies · Physics 2026-05-06 F. Ávila-Vera , V. Motta , E. Mediavilla

A comprehensive new approach is presented for deriving probability densities of physical properties characterizing lens or source that constitute an observed galactic microlensing event. While previously encountered problems are overcome,…

Astrophysics · Physics 2009-11-11 M. Dominik

We consider a contribution of microlensing in X-ray variability of high-redshifted QSOs. Such an effect could be caused by stellar mass objects (SMO) located in a bulge or/and in a halo of this quasar as well as at cosmological distances…

Astrophysics · Physics 2009-11-10 A. F. Zakharov , L. C. Popovic , P. Jovanovic

Gravitational microlensing is currently the only technique that helps study the Galactic distribution of planets as a function of distance from the Galactic center. The Galactic location of a lens system can be uniquely determined only when…

Earth and Planetary Astrophysics · Physics 2021-09-08 Naoki Koshimoto , David P. Bennett , Daisuke Suzuki , Ian A. Bond

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

For a given spatial distribution of the lenses and distribution of the transverse velocity of the lens relative to the line-of-sight, a probability distribution for the lens mass for a single observed event is derived. In addition, similar…

Astrophysics · Physics 2008-02-03 M. Dominik

We consider a contribution of microlensing to the X-ray variability of high-redshifted QSOs. Such an effect could be caused by stellar mass objects (SMO) located in a bulge or/and in a halo of this quasar as well as at cosmological…

Astrophysics · Physics 2007-05-23 A. F. Zakharov , L. C. Popovic , P. Jovanovic

The spatial distribution of compact dark matter in our Galaxy can be determined in a few years of monitoring Galactic globular clusters for microlensing. Globular clusters are the only dense fields of stars distributed throughout the…

Astrophysics · Physics 2009-10-30 James E. Rhoads , Sangeeta Malhotra

We consider the signature and detectability of gravitational microlensing of distant quasars by cosmic strings. Because of the simple image configuration such events will have a characteristic light curve, in which a source would appear to…

Astrophysics · Physics 2009-11-13 Konrad Kuijken , Xavier Siemens , Tanmay Vachaspati

Gravitationally lensed extragalactic sources are often subject to statistical microlensing by stars in the galaxy or cluster lens. Accurate models of the flux statistics are required for inferring source and lens properties from flux…

Astrophysics of Galaxies · Physics 2021-04-27 Liang Dai , Massimo Pascale

We analyze the first-year MACHO collaboration observations of microlensing towards the Galactic center using a new direct likelihood technique that is sensitive to the distribution of the events on the sky. We consider the full set of 41…

Astrophysics · Physics 2007-05-23 Geza Gyuk

Gravitational microlensing constraints on non-standard compact objects are conventionally derived assuming lenses trace the dark matter halo with velocities following a Maxwell-Boltzmann distribution centered around $10^{-3}c$. However, a…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-06 Manish Tamta , Nirmal Raj , Himanshu Verma

We consider a contribution of microlensing to the X-ray variability of high-redshifted QSOs. Cosmologically distributed gravitational microlenses could be localized in galaxies (or even in bulge or halo of gravitational macrolenses) or…

Astrophysics · Physics 2009-11-10 Alexander F. Zakharov , Luka C. Popovic , Predrag Jovanovic

Lensing effects on light rays from point light sources, such like Type Ia supernovae, are simulated in a clumpy universe model. In our universe model, it is assumed that all matter in the universe takes the form of randomly distributed…

Astrophysics · Physics 2008-11-28 Chul-Moon Yoo , Hideki Ishihara , Ken-ichi Nakao , Hideyuki Tagoshi
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