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Observational Tests of MOdified Gravity (MOG)and Non-Local Gravity with Galaxies’ Dynamic

Zhoolideh Haghighi, Mohammad Hossein | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 50833 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Rahvar, Sohrab; Moffat, John
  7. Abstract:
  8. Dark matter is one of the biggest unsolved problems in physics and cosmology. Almost 85 percent of the gravitational matter is not luminous and it’s properties is unknown. In recent decades variety of investigations regarding dark matter has been done which we will mention in the beginning part of this thesis. We continue testing MOdified gravity (MOG), Non-Local-Gravity (NLG) and MOdified Newtonian Dynamics (MOND) in a different scale by using the rotation curves of dwarf galaxies. In addition we compare MOG, MOND and NLG together to see which one better fit observed data. In another investigation that is reported in this thesis, we fit the observed acceleration data of galaxy cluster Abell 1689 with MOG, MOND and NFW model. We show that both MOG and NFW fit the data properly but MOND can’t pass the test successfully.After fitting dwarf galaxies’ rotation curve and acceleration data of Abell1689 cluster we look at structure formation in the universe by means of thermodynamical approach and we show at a critical temperature a first order phase transition happens. Under this phase transition gaseous phase of the system changes to a clumped phase. We investigate this kind of structure formation and phase transition for systems interacting under MONDIAN and Newtonian gravity and we highlight their differences. In the last part of this thesis we establish a model to solve cooling problem in cluster of galaxies. We show that sound crossing time scale in such a systems play an important role and can help solving cooling flow problem.Beside fitting X-ray spectrum, we can have a prediction for cold gas mass and cold fraction profile
  9. Keywords:
  10. Dark Matter ; Structure Formation ; X-Ray Spectrum ; Dwarf Galaxies ; Modified Newtonian Dynamics (MOND) ; Generalized Gravity ; Galaxy Cluster ; Non-Local Gravity

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