The effective Equation of State in Palatini $f(R)$ cosmology
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
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2022
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| _version_ | 1866929255282114560 |
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| author | Camera, S. Capozziello, S. Fatibene, L. Orizzonte, A. |
| author_facet | Camera, S. Capozziello, S. Fatibene, L. Orizzonte, A. |
| contents | We investigate how the cosmological Equation of State can be used for scrutinizing extended theories of gravity, in particular, the Palatini $f(R)$ gravity. Specifically, the approach consists, at first, in investigating the effective Equation of State produced by a given model. Then, the inverse problem can also be considered in view of determining which models are compatible with a given effective Equation of State. We consider and solve some cases and show that, for example, power-law models are (the only models) capable of transforming barotropic Equations of State into effective barotropic ones. Moreover, the form of Equation of State is preserved (only) for $f(R)=R$, as expected. In this perspective, modified Equations of State are a feature capable of distinguishing Extended Gravity with respect to General Relativity. We also investigate quadratic and non-homogeneous effective Equations of State showing, in particular, that they contain the Starobinsky model and other ones. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2212_13825 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | The effective Equation of State in Palatini $f(R)$ cosmology Camera, S. Capozziello, S. Fatibene, L. Orizzonte, A. General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics High Energy Physics - Theory We investigate how the cosmological Equation of State can be used for scrutinizing extended theories of gravity, in particular, the Palatini $f(R)$ gravity. Specifically, the approach consists, at first, in investigating the effective Equation of State produced by a given model. Then, the inverse problem can also be considered in view of determining which models are compatible with a given effective Equation of State. We consider and solve some cases and show that, for example, power-law models are (the only models) capable of transforming barotropic Equations of State into effective barotropic ones. Moreover, the form of Equation of State is preserved (only) for $f(R)=R$, as expected. In this perspective, modified Equations of State are a feature capable of distinguishing Extended Gravity with respect to General Relativity. We also investigate quadratic and non-homogeneous effective Equations of State showing, in particular, that they contain the Starobinsky model and other ones. |
| title | The effective Equation of State in Palatini $f(R)$ cosmology |
| topic | General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics High Energy Physics - Theory |
| url | https://arxiv.org/abs/2212.13825 |