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 Han&#x131;meli</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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