Dark side of the universe in the Stephani cosmology

Hashemi, Seyed Yaser; Jalalzadeh, S.; Riazi, N.

doi:10.1140/epjc/s10052-014-2995-z

Cited by 5 publications

(3 citation statements)

References 36 publications

(47 reference statements)

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“…Slightly different discussion of the models with unfixed k is presented in (Sussman 2000;Hashemi et al 2014) in the frame of investigation of the Stephani universes with physically meaningful equations of state of matter.…”

Section: The Model Of the Universe With The Accelerated Expansionmentioning

confidence: 99%

Accelerated Expansion of the Universe in the Model with Nonuniform Pressure

Kopteva

Bormotova

Churilova

et al. 2019

ApJ

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We present the particular case of the Stephani solution for shear-free perfect fluid with uniform energy density and non-uniform pressure. Such models appeared as possible alternative to the consideration of the exotic forms of matter like dark energy that would cause the acceleration of the universe expansion. These models are characterised by the spatial curvature depending on time. We analyze the properties of the cosmological model obtained on the basis of exact solution of the Stephani class and adopt it to the recent observational data. The spatial geometry of the model is investigated. We show that despite possible singularities, the model can describe the current stage of the universe evolution.

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Section: The Model Of the Universe With The Accelerated Expansionmentioning

confidence: 99%

Accelerated Expansion of the Universe in the Model with Nonuniform Pressure

Kopteva

Bormotova

Churilova

et al. 2019

ApJ

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“…Stelmach and Jakacka produced a fairly comprehensive paper on nonhomogeneity of the universe driven its acceleration under a Stephani cosmology [48]. However, the formalism adopted is not very friendly to our purposes, so that we shall choose the formalism presented by Hashemi et al [14]. So, the metric is given by…”

Section: Stephani Cosmologymentioning

confidence: 99%

“…for k 0 = 0, ±1. Setting the ansatz (128) combined with the perfect uid expression into Einstein's equations we obtain the time-time component of eld equations An extensive derivation of some observational quantities which describe the evolutionary kinematics of the Stephani universe, such as Hubble parameter and deceleration parameter, can be found in reference [14]. From such derivations, for an inhomogeneous Stephani model featured by a time dependent curvature index, with solely dust as the lling up uid component (an oversimplication hardly acceptable), it was reported in the above reference an age of the universe notably larger than the estimated age provided by FLRW models with no exotic matter.…”

Section: (130)mentioning

confidence: 99%

Thesaurus Theoriis Circa Gravitatis et Cetera

Serpa

2017

CALIBRE

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Thesaurus Theoriis Circa Gravitatis et Cetera is a compilation subdivided into two chapters, containing the complete research developed during author's post-doctoral period at the Brazilian Center of Physics Research - CBPF, Rio de Janeiro (2016 - 2017). From the heated discussions that took place in a climate of intense knowledge exchange, additions were made to the original text, making it more translucent to the readers.In the first chapter, the lecture notes related to the Summer Formative Activities -- 2017 were meant to compile the main ideas on gauge field theory and modern cosmology, showing the recent contributions of the author in these areas, especially in classical thermodynamics, supergravity and quantum gravity. Although the author has conducted the work without wishing to exhaust the issues in question, this synthesis provides some essential formal aspects for further studies, with relevant and updated references, as well as indications of classical readings. Special attention was given to author's application of Lyra's geometry, because of its growing importance in quantum cosmology, and to the so-called <<paleogravity>>, a model of supergravity developed by the author with the purpose to offer a classical representation for supergravity that could be made compatible with the quantum theory of spacetime also developed by himself. Also in general cosmology, the emphasis was on inhomogeneous models because of the debate that they open on the validity of the standard model. In this sense, the author presented his perturbative formalism of weak gravitational lensing by defining an inhomogeneous cosmological refractive index within a Lemaître-Tolman universe. Lastly, some remarks on Stephani cosmology were organized in order to expose the most significant features of this approach. During the reading, it shall be possible to observe some title marks indicating items of interest, as well as small side texts with outgivings of renowned authors.In the second chapter, the author expanded the discussion about the quantization of spacetime, previously opened, deepening his phenomenological analysis at the surroundings of supermassive bodies with the aid of the formalism of Green's functions. This approach also opens the way for a broader and dialectical debate on quantum gravity and supergravity, seeking to rescue a physical discourse and not merely the math exercise which has been predominant in some research groups.The author is immensely grateful to the colleagues and external participants for the contributions and affection with which he was received and from which a community of collaborative studies was formed on the most important topics in modern physics. Special thanks goes to our esteemed Professor Helayël, to whom the author directs his highest respects and wishes for a long and brilliant future.

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Probing extra dimensions through cosmological observations of dark energy

Jalalzadeh

Malekolkalami

2023

Physics of the Dark Universe

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Dark side of the universe in the Stephani cosmology

Cited by 5 publications

References 36 publications

Accelerated Expansion of the Universe in the Model with Nonuniform Pressure

Accelerated Expansion of the Universe in the Model with Nonuniform Pressure

Thesaurus Theoriis Circa Gravitatis et Cetera

Probing extra dimensions through cosmological observations of dark energy

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