Higher Dimensional Cosmological Model in Lyra Geometry: Revisited

Singh, G. P.; Kotambkar, S.; Pradhan, Anirudh

doi:10.1142/s0218271803003104

Cited by 21 publications

(14 citation statements)

References 25 publications

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“…Also, in this study for (n + 2) dimensional flat FRW metric, time-like displacement field vector is defined by [49] φ i = (β(t), 0, 0, 0...0)…”

Section: Strange Quark Matter Attached To String Cloud Solutions In Lmentioning

confidence: 99%

Higher Dimensional Topological Defect Solutions with Quark Matter in Gravitation Theories

Çag̃lar¹,

Aygün²

2017

AdAp

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In this paper we have researched higher dimensional flat Friedmann-Robertson-Walker (FRW) cosmological model solutions for string cloud and domain walls coupled with quark and strange quark matters in Lyra and Riemann geometries. We have obtained that string tension density is zero in Lyra and Riemann geometries. Also, the displacement field vector behaves like a cosmological constant in our models. In addition to these, some physical and kinematical quantities have been generalized and discussed in Lyra and Riemann geometries. Also our results are consistent with the results of Yılmaz, Back et al. and Adcox et al. in four dimensions.

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“…Also, in this study for (n + 2) dimensional flat FRW metric, time-like displacement field vector is defined by [49] φ i = (β(t), 0, 0, 0...0)…”

Section: Strange Quark Matter Attached To String Cloud Solutions In Lmentioning

confidence: 99%

Higher Dimensional Topological Defect Solutions with Quark Matter in Gravitation Theories

Çag̃lar¹,

Aygün²

2017

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“…In recent years several authors (see Refs. [15] − [17] and references therein) have studied multidimensional inhomogeneous cosmological models in diferent context.…”

Section: Introductionmentioning

confidence: 99%

Kaluza-Klein Type Robertson Walker Cosmological Model with Dynamical Cosmological Term Λ

Pradhan¹,

Khadekar²,

Patki³

et al. 2007

Int J Theor Phys

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In this paper we have analyzed the Kaluza-Klein type Robertson Walker (RW) cosmological models by considering three different forms of variable Λ: Λ ∼ ȧ a 2 , Λ ∼ ä a and Λ ∼ ρ. It is found that, the connecting free parameters of the models with cosmic matter and vacuum energy density parameters are equivalent, in the context of higher dimensional space time. The expression for the look back time, luminosity distance and angular diameter distance are also derived. This work has thus generalized to higher dimensions the well-known results in four dimensional space time. It is found that there may be significant difference in principle at least, from the analogous situation in four dimensional space time.PACS: 04.50.+h, 98.80.Es

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“…One of the motivations for introducing a decaying lambda is to reconcile the age parameter and the density parameter of the universe with recent observational data. Since spacetime was strongly curved at early times (Planck times), one naturally expects an initial huge value of the cosmological constant of the order of l −2 P = G −1 , where G is the gravitational coupling constant (Pradhan et al 2006;Singh et al 2006). As the universe expands in time, the cosmological constant should decay, thereby leading to the tiny value observed presently.…”

mentioning

confidence: 99%

“…In this short communication, we consider the (n + 2)-dimensional homogeneous universe described by the combination of the standard (1 + 3) FRW metric and n extradimensions as (Pradhan et al 2005;Singh et al 2006) ds 2 = − dt 2 + a 2 (t) dr 2 1 − kr 2 + r 2 × dθ 2 1 + sin 2 θ 1 dθ 2 2 + · · · + sin 2 θ 1 . .…”

mentioning

confidence: 99%

Accelerated expansion of the universe in a non-trivial extra-dimensional topology

El-Nabulsi

2009

Astrophys Space Sci

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The recent observational available data for an accelerated expansion state of the present universe, obtained from distant SNeIa gave strong support to the search of alternative cosmologies. Recently, there have been a number of different attempts to modify Einstein's gravity to yield accelerated expansion at late times. Unfortunately, many of the theoretical models discussed in the literature are plagued with theoretical problems, in particular the singularity problem at the origin of time. In the present work we have analyzed a multidimensional spacetime Friedmann-RobertsonWalker (FRW) model with a decaying cosmological constant and a varying gravitational constant. Many interesting consequences are revealed, in particular the behavior of the scale factor and the shape of the universe in terms of the number of extra dimensions.Keywords Higher-dimensional cosmology · Decaying lambda · Dark energy · Phantom energy PACS 04.50.+h · 11.25.Yb · 98.80.Es · 95.36.+xThe recent available astronomical observations (around 1998 and 1999) of the dynamics of galaxies, cluster of galaxies, of luminosity distances of the Type Ia supernovae (SNeIa) as a function of redshift with redshift in the range −0.10 ≤ z ≤ 0.83, the first acoustic peak of the CMB temperature fluctuations or anisotropies and also the observational results coming from the cosmic microwave background radiation along with the Maxima and Boomerang data favor a spatially flat matter dominated universe undergoing a phase of accelerated expansion dominated by an unknown form of repulsive energy dubbed "Dark Energy (DE)". This ephemeral dark energy should have a negative pressure and has special effects that have only been detected on the largest scales of our Universe and then only in the past ten years (Riess et al. 1998;Perlmutter et al. 1999;Schmidt et al. 1998;Steinhardt et al. 1999;Persic et al. 1996;Carmeli and Kuzmenko 2002;Behar and Carmeli 2002). Presently, as already mentioned, the universe is accelerating in time with the equation of state (EoS) parameter w = p/ρ < −1/3 (ρ and p are respectively the density and pressure of a perfect fluid). However, for models described by w > −1, the null energy condition T μν k μ k ν > 0 is satisfied (T μν is the stress-energy tensor for all time-like vectors k μ ). In contrast to models with w < −1 (phantom energy), the null energy condition ρ + p < 0 with ρ > 0 is violated. Surprisingly, this case is not excluded by observation.In fact, the observed DE is dominated by some fields that have not yet relaxed to their vacuum state. Questions still linger about the nature of dark matter, especially its distribution in the central region of clusters and galaxies. The nature of the dark energy component responsible for the accelerated expansion of the universe is one of the most profound problems in high energy physics. On the other hand the results of large-scale structure surveys and the results of measurements of the masses of galaxies give a best fit for the density parameter for matter of m,0 = 0.3 and consequently ...

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Higher Dimensional Cosmological Model in Lyra Geometry: Revisited

Cited by 21 publications

References 25 publications

Higher Dimensional Topological Defect Solutions with Quark Matter in Gravitation Theories

Higher Dimensional Topological Defect Solutions with Quark Matter in Gravitation Theories

Kaluza-Klein Type Robertson Walker Cosmological Model with Dynamical Cosmological Term Λ

Accelerated expansion of the universe in a non-trivial extra-dimensional topology

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