Fitting Cosmological Data to the Function q(z) from GR Theory: Modified Chaplygin Gas
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| Format: | Artículo científico |
| Langue: | en |
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Sociedade Brasileira de Física
2011
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| author | Alan M. Velasquez-Toribio |
| author_facet | Alan M. Velasquez-Toribio |
| contents | Fitting Cosmological Data to the Function q(z) from GR Theory: Modified Chaplygin Gas Alan M. Velasquez-Toribio Maria Luiza Bedran Física, Astronomía y Matemáticas Modified Chaplygin Gas Observational constraints In the Friedmann cosmology, the deceleration of the expansion q plays a fundamental role. We derive the deceleration as a function of redshift q(z) in two scenarios: ACDM model and modified Chaplygin gas (MCG) model. The function for the MCG model is then fitted to the cosmological data in order to obtain the cosmological parameters that minimize ÷2. We use the Fisher matrix to construct the covariance matrix of our parameters and reconstruct the q(z) function. We use Supernovae Ia, WMAP5, and BAO measurements to obtain the observational constraints. We determined the present acceleration as q0 = .0.65 ± 0.19 for the MCG model using the Union2 dataset of SNeIa, BAO, and CMB and q0 = .0.67 ± 0.17 for the Constitution dataset, BAO and CMB. The transition redshift from deceleration to acceleration was found to be around 0.80 for both datasets. We have also determined the dark energy parameter for the MCG model: nX0 = 0.81 ± 0.03 for the Union2 dataset and nX0 = 0.83 ± 0.03 using the Constitution dataset. 2011 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46421597009 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.1 Vol.41 |
| format | Artículo científico |
| id | redalyc_46421597009 |
| institution | Redalyc |
| language | en |
| publishDate | 2011 |
| publisher | Sociedade Brasileira de Física |
| spellingShingle | Fitting Cosmological Data to the Function q(z) from GR Theory: Modified Chaplygin Gas Alan M. Velasquez-Toribio Física, Astronomía y Matemáticas Modified Chaplygin Gas Observational constraints Fitting Cosmological Data to the Function q(z) from GR Theory: Modified Chaplygin Gas Alan M. Velasquez-Toribio Maria Luiza Bedran Física, Astronomía y Matemáticas Modified Chaplygin Gas Observational constraints In the Friedmann cosmology, the deceleration of the expansion q plays a fundamental role. We derive the deceleration as a function of redshift q(z) in two scenarios: ACDM model and modified Chaplygin gas (MCG) model. The function for the MCG model is then fitted to the cosmological data in order to obtain the cosmological parameters that minimize ÷2. We use the Fisher matrix to construct the covariance matrix of our parameters and reconstruct the q(z) function. We use Supernovae Ia, WMAP5, and BAO measurements to obtain the observational constraints. We determined the present acceleration as q0 = .0.65 ± 0.19 for the MCG model using the Union2 dataset of SNeIa, BAO, and CMB and q0 = .0.67 ± 0.17 for the Constitution dataset, BAO and CMB. The transition redshift from deceleration to acceleration was found to be around 0.80 for both datasets. We have also determined the dark energy parameter for the MCG model: nX0 = 0.81 ± 0.03 for the Union2 dataset and nX0 = 0.83 ± 0.03 using the Constitution dataset. 2011 artículo científico 0103-9733 https://www.redalyc.org/articulo.oa?id=46421597009 en http://www.redalyc.org/revista.oa?id=464 Brazilian Journal of Physics application/pdf Sociedade Brasileira de Física Brazilian Journal of Physics (Brasil) Num.1 Vol.41 |
| title | Fitting Cosmological Data to the Function q(z) from GR Theory: Modified Chaplygin Gas |
| topic | Física, Astronomía y Matemáticas Modified Chaplygin Gas Observational constraints |
| url | https://www.redalyc.org/articulo.oa?id=46421597009 |