scholarly journals Holographic dark energy with varying gravitational constant

2009 ◽  
Vol 679 (3) ◽  
pp. 172-176 ◽  
Author(s):  
Mubasher Jamil ◽  
Emmanuel N. Saridakis ◽  
M.R. Setare
Keyword(s):  
Dark Energy ◽  
Gravitational Constant ◽  
Holographic Dark Energy ◽  
Varying Gravitational Constant

scholarly journals Reconstruction of f(T) and f(R) gravity according to (m, n)-type holographic dark energy

2013 ◽  
Vol 91 (9) ◽  
pp. 703-708 ◽  
Author(s):  
M. Umar Farooq ◽  
Mubasher Jamil ◽  
Davood Momeni ◽  
Ratbay Myrzakulov
Keyword(s):  
Dark Energy ◽  
Solar System ◽  
Gravitational Constant ◽  
Holographic Dark Energy ◽  
Ricci Scalar ◽  
Gravity Models ◽  
Torsion Scalar ◽  
Proposed Model ◽  
Gravity Theories

Motivated by earlier works (Wu and Zhu. Phys. Lett. B, 660, 293 (2008); Daouda et al. Eur. Phys. J. C, 72, 1893 (2012)), we extend them by considering a newly proposed model of (m, n)-type holographic dark energy in f(R) and f(T) gravity theories, where R and T represent Ricci scalar and torsion scalar respectively. Specifically, we reconstruct the two later gravity models and discuss their viability and cosmography. The obtained gravity models are free from ghosts, consistent with local solar system tests, and describe effective positive gravitational constant.

scholarly journals Low-redshift tests of Newtonian cosmologies with a time-varying gravitational constant

2020 ◽  
Vol 497 (4) ◽  
pp. 4407-4415
Author(s):  
Ekim Taylan Hanımeli ◽  
Isaac Tutusaus ◽  
Brahim Lamine ◽  
Alain Blanchard
Keyword(s):  
Dark Energy ◽  
Gravitational Constant ◽  
Second Law ◽  
Time Varying ◽  
Acoustic Oscillations ◽  
Cosmological Observations ◽  
Type Ia ◽  
Varying Gravitational Constant ◽  
Ia Supernovae ◽  
Intrinsic Luminosity

ABSTRACT In this work, we investigate Newtonian cosmologies with a time-varying gravitational constant, G(t). We examine whether such models can reproduce the low-redshift cosmological observations without a cosmological constant, or any other sort of explicit dark energy fluid. Starting with a modified Newton’s second law, where G is taken as a function of time, we derive the first Friedmann–Lemaître equation, where a second parameter, G*, appears as the gravitational constant. This parameter is related to the original G from the second law, which remains in the acceleration equation. We use this approach to reproduce various cosmological scenarios that are studied in the literature, and we test these models with low-redshift probes: type-Ia supernovae (SNIa), baryon acoustic oscillations, and cosmic chronometers, taking also into account a possible change in the supernovae intrinsic luminosity with redshift. As a result, we obtain several models with similar χ2 values as the standard ΛCDM cosmology. When we allow for a redshift-dependence of the SNIa intrinsic luminosity, a model with a G exponentially decreasing to zero while remaining positive (model 4) can explain the observations without acceleration. When we assume no redshift-dependence of SNIa, the observations favour a negative G at large scales, while G* remains positive for most of these models. We conclude that these models offer interesting interpretations to the low-redshift cosmological observations, without needing a dark energy term.

SCALAR FIELDS RECONSTRUCTION OF VISCOUS GDE WITH VARYING G

2014 ◽  
Vol 23 (01) ◽  
pp. 1450002 ◽  
Author(s):  
MOSTAFA SHARIFIAN ◽  
AHMAD SHEYKHI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Gravitational Constant ◽  
Scalar Fields ◽  
Frw Universe ◽  
Ghost Dark Energy ◽  
Scalar Field Models ◽  
Varying Gravitational Constant ◽  
The Universe

In this paper, we first study the effects of the varying gravitational constant G as well as the bulk viscosity on the evolution of the Universe field with pressureless dark matter and ghost dark energy (GDE). Then, we establish a correspondence between viscous GDE and scalar field models of dark energy including quintessence, tachyon, K-essence and dilaton energy density in a flat FRW universe. This correspondence allows us to reconstruct the potential and dynamics of the scalar fields according to the evolution of interacting viscous GDE with varying G.

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