A Machian model of dark energy

Vishwakarma, R. G.

doi:10.1088/0264-9381/19/18/309

Cited by 71 publications

(54 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus a variable Λ is consistent with Mach's principle that for a meaningful spacetime geometry presence of matter is a necessity (Vishwakarma 2002). The conservation of energy-momentum tensor requires…”

Section: Testing a λ ∝ ρ Modelsupporting

confidence: 53%

“…Among them the most elementary is the cosmological constant Λ (Padmanabhan 2003;Peebles and Ratra 2003). Variable Λ models (Carvalho et al 1992;Wetterich 1995;Arbab 1997;Padmanabhan 2001;Vishwakarma 2002;Shapiro & Sola 2004;Dutta Choudhury & Sil 2006) were introduced later in an effort to overcome the fine tuning problem. Among other candidates most popular are different kinds of scalar fields like quintessence (caldwell et al 1998), K-essence (Chiba et al 2000)and phantom fields (caldwell 2002) to name only a few.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A better way to reconstruct dark energy models?

Sil

Som²

2008

Astrophys Space Sci

View full text Add to dashboard Cite

To reconstruct dark energy models the redshift z eq , marking the end of radiation era and the beginning of matter-dominated era, can play a role as important as z t , the redshift at which deceleration parameter experiences a signature flip. To implement the idea we propose a variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model. A popular Λ ∝ ρ dark energy model is chosen for demonstration but found to be unacceptable. An alternative Λ ∝ ρa 3 model is proposed and found to be more close to observation.

show abstract

Section: Testing a λ ∝ ρ Modelsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

A better way to reconstruct dark energy models?

Sil

Som²

2008

Astrophys Space Sci

View full text Add to dashboard Cite

show abstract

“…This relation has been obtained in a number of empirical models [10], [11]. More recently, it was obtained from a model based on the quantum gravitational uncertainty principle and the discrete structure of spacetime at Plank length [12], [13]. The dependence Λ (4) ∼ H 2 explains the current observations successfully and provides a much needed large age of the universe.…”

Section: Introductionmentioning

confidence: 93%

Brane universes with variable G and ₍₄₎

León

2003

Class. Quantum Grav.

View full text Add to dashboard Cite

We investigate the cosmological consequences of a brane-world theory which incorporates time variations in the gravitational coupling G and the cosmological term Λ (4) . We analyze in detail the model whereĠ/G ∼ H and Λ (4) ∼ H 2 , which seems to be favored by observations. We show that these conditions single out models with flat space sections. We determine the behavior of the expansion scale factor, as well as, the variation of G, Λ (4) and H for different possible scenarios where the bulk cosmological constant, Λ (5) , can be zero, positive or negative. We demonstrate that the universe must recollapse, if it is embedded in an Anti-de Sitter five-dimensional bulk, which is the usual case in brane models. We evaluate the cosmological parameters, using some observational data, and show that we are nowhere near the time of recollapse. We conclude that the models with zero and negative bulk cosmological constant agree with the observed accelerating universe, while fitting simultaneously the observational data for the density and deceleration parameters. The age of the universe, even in the recollapsing case, is much larger than in the FRW universe.

show abstract

“…However, imposing this assumption on non-trivial cases would result in losing some important information. For example, taken on the face value, a time-dependent Λ, with matter, implies matter creation and results in a Machian model (Vishwakarma 2002a). However, if one makes an additional assumption of no interaction between T (matter) ik and Λ(t), these features are lost and Λ(t) reduces to a constant.…”

Section: Introductionmentioning

confidence: 99%

Modeling repulsive gravity with creation

Vishwakarma

Narlikar

2007

J Astrophys Astron

View full text Add to dashboard Cite

There is a growing interest in the cosmologists for theories with negative energy scalar fields and creation, in order to model a repulsive gravity. The classical steady state cosmology proposed by Bondi, Gold and Hoyle in 1948, was the first such theory which used a negative kinetic energy creation field to invoke creation of matter. We emphasize that creation plays very crucial role in cosmology and provides a natural explanation to the various explosive phenomena occurring in local (z < 0.1) and extra galactic universe. We exemplify this point of view by considering the resurrected version of this theory -the quasi-steady state theory, which tries to relate creation events directly to the large scale dynamics of the universe and supplies more natural explanations of the observed phenomena.Although, the theory predicts a decelerating universe at the present era, it explains successfully the recent SNe Ia observations (which require an accelerating universe in the standard cosmology), as we show in this paper by performing a Bayesian analysis of the data.

show abstract

A Machian model of dark energy

Cited by 71 publications

References 25 publications

A better way to reconstruct dark energy models?

A better way to reconstruct dark energy models?

Brane universes with variable G and ₍₄₎

Modeling repulsive gravity with creation

Contact Info

Product

Resources

About

A Machian model of dark energy

Cited by 71 publications

References 25 publications

A better way to reconstruct dark energy models?

A better way to reconstruct dark energy models?

Brane universes with variable G and (4)

Modeling repulsive gravity with creation

Contact Info

Product

Resources

About

Brane universes with variable G and ₍₄₎