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Showing 1 to 19 of 19 for “"Microlensing"”.
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Applications of Galactic Microlensing
… is the study of applications of the Galactic Microlensing effect, where the light of a distant star (source) is bend according to Einstein's theory of gravity by the gravitational field of intervening compact mass objects (lenses), creating multiple (however not resolvable) images of the …
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Stochastic Microlensing: Mathematical Theory and Applications
<p>Stochastic microlensing is a central tool in probing dark matter on galactic scales. From first principles, we initiate the development of a mathematical theory </p><p>of stochastic microlensing. We first construct a natural probability space for stochastic microlensing and characterize the …
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The detection of gravitational microlensing anomalies
The detection and measurability of microlensing anomalies including planet detection, resolved source, blending and parallax effects are investigated by way of an extensive computer simulation as a function of the observation strategy. The most efficient strategy has a planet detection probability …
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Statistical analyses of gravitational microlensing probability densities
Gravitational microlensing is a powerful modelling tool, that is essential in accurately understanding the lensing behavior of astronomically strong lensed objects. Using Joachim Wambsganss micro-magnification maps, we discuss the creation of a Monte-Carlo tool that can determine the likelihood for …
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Gravitational microlensing and the search for extrasolar planets
… is aimed at tackling binary gravitational microlensing events. Since the early conception of gravitational lensing before Einstein’s General Theory of Relativity, physicists and astronomers of the early 18th century speculated that light, if treated as particle, can be affected by …
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A novel algorithm for analysing gravitational microlensing events
… to perform autonomous fitting of gravitational microlensing lightcurves. The algorithm combines features of extant evolutionary algorithms with some novel ones, and fares well on the problem of fitting binary lens microlensing lightcurves, as well as on a number of other difficult optimisation …
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Zooming in on quasar accretion disks using chromatic microlensing
… imaging, and takes advantage of the presence of microlensing perturbations to the magnifications of the lensed images. The dependence of these perturbations on the angular size of the source, combined with the temperature structure of quasar accretion disks, causes the flux ratio anomalies due to …
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Fitting binary lens gravitational microlensing events with example-based algorithms
Fitting binary lens models to gravitational microlensing event is currently a time consuming and labour-intensive process. Example-based algorithms more commonly used in the field of data mining were applied to simulatded and observed light curves in order to facilitate the fitting of a …
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Size is everything : universal features of quasar microlensing with extended sources
… fluctuations of images in lens systems due to microlensing. We do this by convolving a variety of accretion disk models (including Gaussian disks, uniform disks, "cones," and a Shakura-Sunyaev thermal model) with two magnification patterns in the source plane, one with convergence [kappa] = 0.4 …
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The role of binary stars in searches for extrasolar planets by microlensing and astrometry
When Galactic microlensing events of stars are observed, one usually measures a symmetric light curve corresponding to a single lens, or an asymmetric light curve, often with caustic crossings, in the case of a binary lens system. In principle, the fraction of binary stars at a certain separation …
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Gravitational Lensing in the Solar Neighbourhood and Towards the Milky Way Bulge
… is concerned with looking for and characterizing microlensing events in two places that are relatively unexplored. Leveraging astrometry from the Gaia satellite, I search for predicted close stellar alignments by lenses in the solar neighbourhood that will give rise to a microlensing event. Using …
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Mass and Distance Estimation Simulations for the Nancy Grace Roman Space Telescope Using PyLIMASS and a Case Study on Intellectual Property Frameworks in Space Collaborations
Gravitational microlensing is a phenomenon in which a foreground star or planet briefly magnifies light from a more distant background star. This effect enables the discovery of exoplanets that are otherwise undetectable, including those orbiting faint hosts and at large separations. Microlensing …
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The red clump stars as a distance indicator : review and application
… of stars simultaneously observed by the OGLE microlensing project which yields well-defined red clump structures in their colour magnitude diagrams. We have used data obtained at Sutherland in July 1997, in collaboration with the PLANET microlensing project. It was hoped that the observation of …
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The distribution of dark matter at large scales and in gravitational lenses
… matter substructure (DMS) millilensing and PBH microlensing. I describe the first flux density ratio measurement of B1422+231 in the millimeter wave band using the Atacama Large Millimeter Array (ALMA). We find a flux density ratio for B1422+231 at 233 GHz similar to those measured in radio and …
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Dynamics and evolution of dense stellar systems
… Using a recent null detection of planetary-mass microlensing events in M22, I find an upper limit of 25% at the 63% confidence level for the current mass fraction of M22 in the form of very low-mass objects. Turning to more realistic clusters, I present a study of the evolution of clusters …
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Gravitational Lensing and the Maximum Number of Images
Gravitational lensing, initially a phenomenon used as a solid confirmation of General Relativity, has defined itself in the past decade as a standard astrophysical tool. The ability of a lensing system to produce multiple images of a luminous source is one of the aspects of gravitational lensing …
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Cosmology through gravitational lenses
In dieser Dissertation nutze ich den Gravitationslinseneffekt, um eine Reihe von kosmologischen Fragen zu untersuchen. Der Laufzeitunterschied des Gravitationslinsensystems HE1104-1805 wurde mit unterschiedlichen Methoden bestimmt. Zwischen den beiden Komponenten erhalte ich einen Unterschied von …
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Anwendung des Mikrogravitationslinseneffekts zur Untersuchung astronomischer Objekte
Die Untersuchung mikrogelinster astronomischer Objekte ermöglicht es, Informationen über die Größe und Struktur dieser Objekte zu erhalten. Im ersten Teil dieser Arbeit werden die Spektren von drei gelinsten Quasare, die mit dem Potsdamer Multi Aperture Spectrophotometer (PMAS) erhalten wurden, auf …