Testes cosmológicos aplicados a modelos de energia escura
A significant observational effort has been directed to investigate the nature of the so-called dark energy. In this dissertation we derive constraints on dark energy models using three different observable: measurements of the Hubble rate H(z) (compiled by Meng et al. in 2015.); distance modulus...
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| Formato: | Dissertação |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/21086 |
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| Resumo: | A significant observational effort has been directed to investigate the nature
of the so-called dark energy. In this dissertation we derive constraints
on dark energy models using three different observable: measurements of the
Hubble rate H(z) (compiled by Meng et al. in 2015.); distance modulus of
580 Supernovae Type Ia (Union catalog Compilation 2.1, 2011); and the observations
of baryon acoustic oscilations (BAO) and the cosmic microwave
background (CMB) by using the so-called CMB/BAO of six peaks of BAO
(a peak determined through the Survey 6dFGS data, two through the SDSS
and three through WiggleZ). The statistical analysis used was the method
of the χ2 minimum (marginalized or minimized over h whenever possible)
to link the cosmological parameter: m, ω and δω0. These tests were
applied in two parameterization of the parameter ω of the equation of state
of dark energy, p = ωρ (here, p is the pressure and ρ is the component of
energy density). In one, ω is considered constant and less than -1/3, known
as XCDM model; in the other the parameter of state equantion varies with
the redshift, where we the call model GS. This last model is based on arguments
that arise from the theory of cosmological inflation. For comparison it was also made the analysis of model CDM. Comparison of cosmological models with different observations lead to different optimal settings. Thus,
to classify the observational viability of different theoretical models we use two criteria information, the Bayesian information criterion (BIC) and the Akaike information criteria (AIC). The Fisher matrix tool was incorporated into our testing to provide us with the uncertainty of the parameters of each
theoretical model. We found that the complementarity of tests is necessary inorder we do not have degenerate parametric spaces. Making the minimization process we found (68%), for the Model XCDM the best fit parameters are m = 0.28 ± 0, 012 and ωX = −1.01 ± 0, 052. While for Model GS the best settings are m = 0.28 ± 0, 011 and δω0 = 0.00 ± 0, 059. Performing a marginalization we found (68%), for the Model XCDM the best fit parameters are m = 0.28 ± 0, 012 and ωX = −1.01 ± 0, 052. While for Model GS the best settings are M = 0.28 ± 0, 011 and δω0 = 0.00 ± 0, 059. |
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