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Chi-Squared Analysis of Measurements of Two Cosmological Parameters Over Time
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
2019 (English)Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

For this project, a historical statistical analysis of the Amplitude of Mass Fluctuations ($\sigma_8$) and Hubble's Constant ($H_0$) parameters in the Standard Cosmological Model was carried out to determine whether or not the given error bars truly represent the dispersion of values. It was found through analysis of the Chi-Squared ($\chi^2$) values of the data that for $\sigma_8$ (60 data points and $\chi^2$ between 183.167 and 189.037) that the associated probability Q is extremely low, with $Q = 1.5597*10^{-15}$ for the weighted average and $Q = 1.2107*10^{-14}$ for the best fit of the data. This was also the case for the $\chi^2$ values (163 data points and $\chi^2$ between 484.3977 and 575.655) of $H_0$, where $Q = 4.2176*10^{-34}$ for the linear fit of the data and $Q = 1.0342*10^{-47}$ for the weighted average of the data. Through further analysis, it is shown in question, a linear fit is a better estimate of the data than the weighted average. The general conclusion is that the statistical error bars have been underestimated (in around 20\% of the measurements), or the systematic errors were not properly taken into account.

Place, publisher, year, edition, pages
2019. , p. 23
Series
FYSAST ; FYSPROJ1150
Keywords [en]
Cosmology Chi Squared Hubble Constant Amplitude of Mass Fluctuations Statistical Analysis
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:uu:diva-399031OAI: oai:DiVA.org:uu-399031DiVA, id: diva2:1377443
External cooperation
Martín López Corredoira
Educational program
Master Programme in Physics
Presentation
2019-10-07, Ångströmlaboratoriet - House 6, Floor 3, Lägerhyddsvägen 1, Uppsala, 17:30 (English)
Supervisors
Examiners
Available from: 2019-12-17 Created: 2019-12-11 Last updated: 2019-12-17Bibliographically approved

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