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Changing the Sound Horizon in Early Universe to Reconcile the Hubble Tension and Cosmological Large Scale Structure Observations

Khalaj Masoumi, Yasaman | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55737 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Baghram, Shant
  7. Abstract:
  8. The Standard Model ΛCDM which includes cold dark matter and cosmological constant components provides a good fit to a large span of cosmological data and large scale structures. Recent results of local measurements of Hubble constant rely on observations of type 1A supernovae have shown 4σ tension comparing H0 to the value inferred from cosmic microwave background observations assuming ΛCDM. The Hubble parameter appears in the cosmic microwave background as one of the standard cosmological model parameters. If these observations are not the result of statistical or systematic error, They could represent new physics beyond the standard ΛCDM cosmological model. The purpose of this thesis is to study models beyond the standard model in the early universe to change the sound horizon on cosmic background radiation to relieve the Hubble tension. In the following, we study the merger rate of primordial black holes in the early universe. They can be mimicked by a dark energy dark matter interacting model. This energy transfer is used to change the sound horizon. The rate of mergers is studied due to the profile of dark matter halo and the number density of dark matter affected by the initial modified power spectrum
  9. Keywords:
  10. Cosmology ; Hubble Constant Stress ; Early Universe ; Cosmological Structure Formation ; Cosmology Standard Model ; Cosmic Microwave Background (CMB)

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