Data Analysis of Gaia and OGLE Projects and Determination Properties of Gravitational Microlensing

Mozaheb, Saeed | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56761 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Rahvar, Sohrab
  7. Abstract:
  8. At the beginning of the 20th century, Albert Einstein introduced the equations of general relativity, opening a new avenue for investigating various phenomena. One of the predictions of these equations, gravitational lensing, was observed by Eddington during his lifetime, confirming the theory's ability to describe nature. Gravitational lensing can be categorized into three types: strong lensing, weak lensing, and microlensing. The current focus of research is on observing the separation phenomenon in gravitational microlensing. The observation of gravitational microlensing provides valuable insights into the composition of celestial bodies in the universe. Calculating the mass of different objects is a challenging problem in astrophysics. Simply observing light and examining the spectrum of stars does not provide clear information about their mass. Natural phenomena like gravitational lensing, which allow for mass calculations, are therefore crucial. Additionally, determining the mass of various objects enables the study of the distribution of dark matter in galaxies.\\ Calculating the mass solely based on the light curve of gravitational microlensing events is not possible. Hence, different observational disturbances observed in some events, such as the parallax effect, finite size effect, and lens and source separation, are taken into account. In this research, an attempt was made to observe the separation of gravitational microlensing events by collating data from the Gaia space telescope and OGLE telescope. Subsequently, Hubble Space Telescope data was used to repeat this observation with higher angular resolution. Although this cross-match resulted in a rich database of gravitational microlensing phenomena, the separation phenomenon was not observed in any of the observational data. Finally, simulations of these events were conducted using the Monte Carlo method to assess the probability of observing the separation phenomenon with various active telescopes and projects such as Hubble and ALMA. Suggestions for future research, utilizing the collated data, were also presented. Considering the necessary visibility conditions for the separation, the visibility of events was evaluated for various observational instruments based on their angular detection. Consequently, the Hubble telescope and the ALMA radio telescope were identified as the most suitable choices for observing the separation phenomenon in the future
  9. Keywords:
  10. General Relativity Theory ; Gravitational Microlensing ; Separation ; Optical Gravitational Lensing Experiment (OGLE) ; Source and Lens Separation ; Cross-Match

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