The Spectrum of Gravitational Waves in an f(R) Model with a Bounce

Bouhmadi-López, Mariam; Morais, João; Henriques, Alfredo B.

doi:10.1007/978-3-642-40157-2_16

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…While it might be possible that our universe will be inflating forever as a boring ΛCDM universe, where so far no convincing solution to the true nature of the cosmological constant is available at hand, it might be that dark energy is an evolving component and in particular of a phantom-like nature [1]. Within this context, it is well known that different future doomsdays are observationally possible [4], being what is known as the LSBR one of the possibilities. This abrupt event which is not a true cosmological singularity as it happens at an infinite cosmic time, though the scalar curvature blows up when approaching it, share some feature with the Big Rip singularity on the sense that at a finite cosmic time from now all the known bounded structure would be destroyed [3].…”

Section: Discussionmentioning

confidence: 99%

“…In fact, the current cosmological data [1,2] are compatible with a future doomsday, not predicted by the conventional ΛCDM model. One of the mildest possible future doomsdays is what is known as the Little Sibling of the Big Rip (LSBR) [3,4]. It is an abrupt event at an infinite cosmic time, therefore it is not a singularity, however all the known structures in our universe would be ripped apart at a finite cosmic time if a LSBR would be the final stage of our universe the LSBR [3].…”

Section: Contentsmentioning

confidence: 99%

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Quantum behavior of the “Little Sibling” of the Big Rip induced by a three-form field

Bouhmadi-López

Brizuela

Garay

2018

J. Cosmol. Astropart. Phys.

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A canonical quantizationà la Wheeler-DeWitt is performed for a model of three-form fields in a homogeneous and isotropic universe. We start by carrying out the Hamiltonian formalism of this cosmological model. We then apply this formalism to a Little Sibling of the Big Rip (LSBR), an abrupt event milder than a Big Rip and that is known to be generic to several minimally coupled three-form fields for a variety of potentials. We obtain a set of analytical solutions of the Wheeler-DeWitt equation using different analytical approximations and explore the physical consequences of them. It turns out that there are quantum states where the wave function of the universe vanishes, i.e. the DeWitt condition is fulfilled for them. Given that this happens only for some subset of solutions of the Wheeler-DeWitt equation, this points out that the matter inducing the LSBR is equally important in the process as, it has been previously shown, a minimally coupled phantom scalar field feeding classically a LSBR is smoothed at the quantum level, i.e. all the quantum states lead to a vanishing wave function.

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Section: Discussionmentioning

confidence: 99%

Section: Contentsmentioning

confidence: 99%

Quantum behavior of the “Little Sibling” of the Big Rip induced by a three-form field

Bouhmadi-López

Brizuela

Garay

2018

J. Cosmol. Astropart. Phys.

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“…167 Specifically, it has been shown that there are distinctive (oscillatory) signals on the primordial gravitational wave spectrum for very low frequencies in f (R)-gravity; such signals correspond to modes that are currently entering the horizon. 168 Detailed studies regarding the potential role of STVG in producing cosmological bounces are still missing, likely because of the complexity of the theory. Recently, Jamali et al 169 have shown that extra fields in STVG cannot provide a late time accelerated expansion.…”

Section: Singularities and Beyondmentioning

confidence: 99%

Astrophysical Constraints on Strong Modified Gravity

Pérez

Romero

2020

Topics on Strong Gravity

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We offer a discussion on the strong field regime predictions of two families of theories that deviate from General Relativity in different aspects: f (R)-gravity and Scalar-Tensor-Vector Gravity (STVG). We discuss astrophysical effects in models based upon both matter and vacuum solutions of such theories. In particular, we analize neutron star structure and the constraints on the parameters of the theories introduced by the latest observations. We also review black hole solutions and several astrophysical consequences of them, including accretion disks and jets. Finally, we report on the implications of the detection of various gravitational wave events for these theories.

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“…Moreover, phantom energy could also lead to the occurrence of a Big Freeze singularity [10,11], which is characterised by a divergence of the Hubble parameter and its cosmic time derivative but at a finite and non-vanishing scale factor. These investigations have renewed the interest in studying new cosmic singularities, which are not necessarily due to the existence of a phantom fluid, and there is a whole bunch of them (for a recent account on this topic, please see reference [12]).…”

Section: Introductionmentioning

confidence: 99%

f(R) quantum cosmology: Avoiding the big rip

2018

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Extended theories of gravity have gathered a lot of attention over the last years, for they not only provide an excellent framework to describe the inflationary era but also yields an alternative to the elusive and mysterious dark energy. Among the different extended theories of gravity, on this work we focus on metric f (R) theories. In addition, it is well known that if the late-time acceleration of the universe is stronger than the one induced by a cosmological constant then some future cosmic singularities might arise, being the Big Rip the most virulent one. Following this reasoning, on this work, we analyse the Big Rip singularity in the framework of f (R) quantum geometrodynamics. Invoking the DeWitt criterion, i. e. that the wave function vanishes at the classical singularity, we proof that a class of solutions to the Wheeler-DeWitt equation fulfilling this condition can be found. Therefore, this result hints towards the avoidance of the Big Rip in metric f (R) theories of gravity.

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The Spectrum of Gravitational Waves in an f(R) Model with a Bounce

Cited by 6 publications

References 19 publications

Quantum behavior of the “Little Sibling” of the Big Rip induced by a three-form field

Quantum behavior of the “Little Sibling” of the Big Rip induced by a three-form field

Astrophysical Constraints on Strong Modified Gravity

f(R) quantum cosmology: Avoiding the big rip

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