Can dark energy emerge from a varying $G$ and spacetime geometry?. (arXiv:2201.04629v1 [gr-qc])

<a href="http://arxiv.org/find/gr-qc/1/au:+Hanimeli_E/0/1/0/all/0/1">Ekim Taylan Hanımeli</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Tutusaus_I/0/1/0/all/0/1">Isaac Tutusaus</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Lamine_B/0/1/0/all/0/1">Brahim Lamine</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Blanchard_A/0/1/0/all/0/1">Alain Blanchard</a>

The accelerated expansion of the Universe implies the existence of an energy

contribution known as dark energy. Associated with the cosmological constant in

the standard model of cosmology, the nature of this dark energy is still

unknown. We will discuss an alternative gravity model in which this dark energy

contribution emerges naturally, as a result of allowing for a time-dependence

on the gravitational constant, $G$, in Einstein’s Field Equations. With this

modification, Bianchi’s identities require an additional tensor field to be

introduced so that the usual conservation equation for matter and radiation is

satisfied. The equation of state of this tensor field is obtained using

additional constraints, coming from the assumption that this tensor field

represents the space-time response to the variation of $G$. We will also

present the predictions of this model for the late-Universe data, and show that

the energy contribution of this new tensor is able to explain the accelerated

expansion of the Universe without the addition of a cosmological constant.

Unlike many other alternative gravities with varying gravitational strength,

the predicted $G$ evolution is also consistent with local observations and

therefore this model does not require screening. We will finish by discussing

possible other implications this approach might have for cosmology and some

future prospects.

The accelerated expansion of the Universe implies the existence of an energy

contribution known as dark energy. Associated with the cosmological constant in

the standard model of cosmology, the nature of this dark energy is still

unknown. We will discuss an alternative gravity model in which this dark energy

contribution emerges naturally, as a result of allowing for a time-dependence

on the gravitational constant, $G$, in Einstein’s Field Equations. With this

modification, Bianchi’s identities require an additional tensor field to be

introduced so that the usual conservation equation for matter and radiation is

satisfied. The equation of state of this tensor field is obtained using

additional constraints, coming from the assumption that this tensor field

represents the space-time response to the variation of $G$. We will also

present the predictions of this model for the late-Universe data, and show that

the energy contribution of this new tensor is able to explain the accelerated

expansion of the Universe without the addition of a cosmological constant.

Unlike many other alternative gravities with varying gravitational strength,

the predicted $G$ evolution is also consistent with local observations and

therefore this model does not require screening. We will finish by discussing

possible other implications this approach might have for cosmology and some

future prospects.

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