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The luminosity variation of a stellar source due to the gravitational microlensing effect can be considered also if the light rays are defocused (instead of focused) toward the observer. In this case, we should detect a gap instead of a…

Quasar microlensing analyses implicitly generate a model of the variability of the source quasar. The implied source variability may be unrealistic yet its likelihood is generally not evaluated. We used the damped random walk (DRW) model…

Instrumentation and Methods for Astrophysics · Physics 2017-11-01 S. S. Tie , C. S. Kochanek

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

Although micro-lensing of macro-lensed quasars and supernovae provides unique opportunities for several kinds of investigations, it can add unwanted and sometimes substantial noise. While micro-lensing flux anomalies may be safely ignored…

Astrophysics of Galaxies · Physics 2021-12-01 Luke Weisenbach , Paul Schechter , Sahil Pontula

Microlensing is generally studied in the geometric optics limit. However, diffraction may be important when nearby substellar objects lens occult distant stars. In particular the effects of diffraction become more important as the…

Astrophysics of Galaxies · Physics 2010-10-05 Jeremy S. Heyl

Of all planet-finding techniques, microlensing is potentially the most sensitive to Earth-mass planets. However, microlensing lightcurves generically yield only the planet-star mass ratio: the mass itself is uncertain to a factor of a few.…

Astrophysics · Physics 2009-11-07 Andrew Gould , B. Scott Gaudi , Cheongho Han

Recent discussion of the effects of finite source size on high magnification microlensing events due to MACHOs motivates a study into the feasibility of observing such effects and extracting the source radius. Simulated observations are…

Astrophysics · Physics 2009-10-28 Eric Peng

(abridged) Using the particularly long gravitational microlensing event OGLE-2014-BLG-1186 with a time-scale $t_\mathrm{E}$ ~ 300 d, we present a methodology for identifying the nature of localised deviations from single-lens point-source…

Extreme microlensing events, defined as events with maximum magnification $A_\max\gsim 200$ are a potentially powerful probe of the mass spectrum and spatial distribution of objects along lines of sight toward the Galactic bulge. About 75…

Astrophysics · Physics 2007-05-23 Andrew Gould

Diffraction is important when nearby substellar objects gravitationally lens distant stars. If the wavelength of the observation is comparable to the Schwarzschild radius of lensing object, diffraction leaves an observable imprint on the…

Instrumentation and Methods for Astrophysics · Physics 2013-02-26 Jeremy S. Heyl

Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Jun Zhang

We use archival data of NASA's Chandra X-ray telescope to compile an X-ray light curve of all four images of the quadruply lensed quasar Q2237+0305 (z=1.695) from January 2006 to January 2007. We fit simulated point spread functions to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 F. Zimmer , R. W. Schmidt , J. Wambsganss

Gravitational microlensing has proven to be a powerful tool in the study of quasars, providing some of the strongest limits on the scales of structure in the central engine. Typically sources are considered to be smoothly varying on some…

Astrophysics · Physics 2009-11-10 Geraint F. Lewis

During microlensing events with a small impact parameter, the amplification of the source flux is sensitive to the surface brightness distribution of the source star. Such events provide a means for studying the surface structure of target…

Astrophysics · Physics 2009-10-31 David Heyrovsky , Dimitar Sasselov

Due to the high efficiency of planet detections, current microlensing planet searches focus on high-magnification events. High-magnification events are sensitive to remote binary companions as well and thus a sample of wide-separation…

We estimate the optical depth, time-scale distribution and fraction of microlensing events originating from sources in the Sagittarius dwarf galaxy (Sgr) lensed by deflectors in the Milky Way. These events have a time-scale longer by a…

Astrophysics · Physics 2009-11-06 Patrick Cseresnjes , Christophe Alard

The microlensing effect has developed into a powerful technique for a diverse range of applications including exoplanet discoveries, structure of the Milky Way, constraints on MAssive Compact Halo Objects, and measurements of the size and…

Astrophysics of Galaxies · Physics 2021-12-22 Xuechun Chen , Yiping Shu , Guoliang Li , Wenwen Zheng

The method devised by Lewis et al. (1993) for calculating the light curve of a microlensed point source is expanded to two dimensions to enable the calculation of light curves of extended sources. This method is significantly faster than…

Astrophysics · Physics 2009-10-31 J. S. B. Wyithe , R. L. Webster