Confirmation of cosmological scenarios
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Date
2024-07-10
Authors
Λιόνας, Δημήτριος
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Abstract
The most serious difficulty that has plagued the field of Cosmology in
recent years is the Hubble tension. With technological advancements
in our observational tools, there has been a rising disparity in the
measurements of the expansion rate of the universe. Most notably, the
Hubble parameter given by the Planck collaboration differs significantly
from the measurements obtained from the local distance ladder. This
tension is above 4σ, making the probability of it occurring by chance very
slim. To alleviate this tension, in this thesis we utilize the Horndeski
theory. By introducing an extra degree of freedom in the form of a
scalar field, we will show that it is possible for H(z) obtained from
our model to coincide with HΛCDM(z) of WMAP at z = zCMB ≈ 1100,
namely H(z → zCMB) ≈ HΛCDM(z → zCMB), while still allowing for
H(z → 0) > HΛCDM(z → 0) as predicted from local measurements. We
will use parameter inference methods to estimate the best values for the
parameters and test this model for validity using model selection criteria.
Description
Keywords
Cosmology, Modified gravity, Cosmological parameters