Sharif Digital Repository

When in a binary system one of the stars passes behind another star eclipsing binary will occur and light’s intensity will decrease. Now with assumption that one of its component be Black Hole When another star passes behind of it the star’s light is amplified by Microlensing.With detection of this amplification we can find black hole’s mass. Of course in this phenomenon the degeneracy will be broken completely and we can obtain all of the quantity. From another specification of this event we can call the shortness and repetitive of Einestein’time .The Einestein’s time is approximately a few hours and depending on system’s period this event will be repeated in specific time.Finally Black... 

After Supernovae and gamma-ray bursts, Quasars are the brightest in the Universe. They are powered by supermassive black holes which lie at the center of the galaxies. Perturbations in space-time metrics by massive galaxies near the line of sight of the quasar can lead to strong lensing and create multiple pictures. Gravitationally lensed quasar systems yield abundant data sets for astrophysical and cosmological experimentation. In this thesis survey results of the multiply lensed SDSS J1206+4332 is studied. Candidate phenomenons are microlensing and gravitational grating. Gravitational grating studies the interaction of electromagnetic wave and gavitational wave in both geometric and wave... 

Gravitational microlensing with the binary lenses are one the tools for detection of exoplanets. Due to the degeneracy nature of the solutions for the observed light curves additional features such as parallax and finite-size effects help to break the degeneracy. Here in this work we introduce the application of frequency shift effect in the microlensing observations where for the single lens, it has been studied in [5] .In this work our purpose is to study the frequency shifts in binary lenses. Therefore, after reviewing the frequency shift in single gravitational lens systems, we will study this phenomenon in binary systems.In binary lenses, which are mainly used to detect extrasolar... 

The finite-size effect in gravitational microlensing provides a possibility to measure the variation of surface brightness of stars from centre to limb which is called limb darkening profile. Measuring limb darkening profile provides information about star atmosphere. It is also useful in other fields of astrophysics. In this thesis we develop a numerical method to recover limb darkening of source stars from single lens microlensing light curves with finite source effect in which the lens transits the source disk. We use the Finite Element Method (FEM) as an inversion tool for discretization and inversion of the finite source effect integral equation. This method makes no explicit assumption...