Abstract:
Dark energy cosmology is considered in a modified Gauss-Bonnet model of
gravity with and without a scalar field. It is shown that these generalizations of General
Relativity endow it with a very rich cosmological structure: it may naturally lead to
an effective cosmological constant, quintessence or phantom cosmic acceleration, with
the possibility to describe the transition from a decelerating to an accelerating phase
explicitly. It is demonstrated here that these modified GB and scalar-GB theories are
perfectly viable as cosmological models. They can describe the _CDM cosmological
era without any need for a cosmological constant. Specific properties of these theories
of gravity in different particular cases, such as the de Sitter one, are studied.
Description:
Dark energy cosmology is considered in a modified Gauss-Bonnet model of
gravity with and without a scalar field. It is shown that these generalizations of General
Relativity endow it with a very rich cosmological structure: it may naturally lead to
an effective cosmological constant, quintessence or phantom cosmic acceleration, with
the possibility to describe the transition from a decelerating to an accelerating phase
explicitly. It is demonstrated here that these modified GB and scalar-GB theories are
perfectly viable as cosmological models. They can describe the _CDM cosmological
era without any need for a cosmological constant. Specific properties of these theories
of gravity in different particular cases, such as the de Sitter one, are studied.
