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Resolving stellar surfaces with binary gravitational microlensing
Pejcha, Ondřej ; Heyrovský, David (advisor) ; Dovčiak, Michal (referee)
Binary gravitational microlensing has demonstrated excellent prospects for studying the surface brightness distribution of stars. In this work we study the extended-source eects that aect the amplication of the source ux. We identify regions in the geometry that are sensitive to the extended source and nd previously unknown areas between facing cusps of multi-part caustics. We nd out that the probability of detecting the extended-source eect can be as much as two times higher than the probability of observing pure caustic crossing. We explore the chromaticity of binary microlensing and compare two classes of models of limb darkening. We describe spectral changes during binary microlensing and compare their amplitude to the point-lens case. Finally, we investigate the linear fold approximation and nd signicant residuals even in cases favorable for the method.
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Binary pulsars - astrophysical laboratories (not only) of theory of general relativity
Beňová, Zuzana ; Kofroň, David (advisor) ; Karas, Vladimír (referee)
Title: Binary pulsars - astrophysical laboratories of general relativity Author: Zuzana Beňová Department: Institute of Theoretical Physics Supervisor: Mgr. David Kofroň, PhD Supervisor's e-mail address: d.kofron@gmail.com The mail concern of this work are tests of relativistic theories of gravitation (mainly GR) that are made by employing compact double-pulsars. The first part is devoted to basic tests and effects of relativistic theories: gravitatio- nal redshift, orbital period decay due to the emission of gravitational waves, periastron shift, Shapiro effect and precession of rotation axis. A brief de- scription of pulsars (in general) and double-pulsars follows. We describe the orbital parameters and their post-Keplerian corrections. Finally, the theory is demonstrated on the unique double-pulsar PSR J037-3039 A/B which was discovered only 7 years ago. Keywords: relativistic theories, double pulsar, tests of GR
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Gravitational microlensing by a few-body system
Daněk, Kamil ; Dovčiak, Michal (referee) ; Heyrovský, David (advisor)
In the present work we study gravitational microlenses consisting of a few point masses. We present the theoretical framework of n-point-mass lensing, and followup by a more detailed description of binary and triple lenses. We demonstrate the analysis of critical curves and caustics of the bojary lens and apply the same approach to the case of triple lenses. We divided several two-dimensional cuts of the parameter space into areas with different topology of critical curves. We studied the amplification of a source located in the vicinity of interesting parts of the caustic. We tested the applicability of an approximation for the amplification at the intersection of two folds. Finally, we applied the formalism to the case of the observed triple-lens microlensing event OGLE-2006-BLG-109.
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