Brane models with a Ricci-coupled scalar field

Bogdanos, C.; Dimitriadis, Anastasios; Tamvakis, K.

doi:10.1103/physrevd.74.045003

Cited by 54 publications

(82 citation statements)

References 27 publications

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“…Rather, a finite thickness should be assumed for the brane. Such thick brane models were already studied, either with a scalar field on the thick brane [45], [46] or an other matter form with transverse pressure component [47], [48], meant to replace the brane tension. We expect that the emergence and increase without bounds of the tension in the collapsing fluid (23) could be derived in a suitable limit of some thick brane model, from the interaction of the fluid with the matter configuration of the thick brane.…”

Section: Discussionmentioning

confidence: 99%

Black holes and dark energy from gravitational collapse on the brane

Gergely

2007

J. Cosmol. Astropart. Phys.

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The gravitational collapse of a pressureless fluid in general relativity (Oppenheimer-Snyder collapse) results in a black hole. The study of the same phenomenon in the brane-world scenario has shown that the exterior of the collapsing dust sphere cannot be static. We show that by allowing for pressure, the exterior of a fluid sphere can be static. The gravitational collapse on the brane proceeds according to the modified gravitational dynamics, turning the initial nearly dust-like configuration into a fluid with tension. The tension arises from the non-linearity of the dynamical equations in the energy-momentum tensor, and it vanishes in the general relativistic limit. Below the horizon the tension turns the star into dark energy. This transition occurs right below the horizon for astrophysical black holes and far beyond the horizon for intermediate mass and galactic black holes. Further, both the energy density and the tension increase towards infinite values during the collapse. The infinite tension however could not stop the formation of the singularity.

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Section: Discussionmentioning

confidence: 99%

Black holes and dark energy from gravitational collapse on the brane

Gergely

2007

J. Cosmol. Astropart. Phys.

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“…The non-zero components of the 5D Einstein equation read [324,325,326,327,328,329,330,331,332,333,334,335,33 37) where primes indicate derivatives with respect to y and dots derivatives with respect to t. On the brane we assume a perfect fluid…”

Section: Quintom De In the Braneworldmentioning

confidence: 99%

Quintom cosmology: Theoretical implications and observations

et al. 2010

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We review the paradigm of quintom cosmology. This scenario is motivated by the observational indications that the equation of state of dark energy across the cosmological constant boundary is mildly favored, although the data are still far from being conclusive. As a theoretical setup we introduce a no-go theorem existing in quintom cosmology, and based on it we discuss the conditions for the equation of state of dark energy realizing the quintom scenario. The simplest quintom model can be achieved by introducing two scalar fields with one being quintessence and the other phantom. Based on the double-field quintom model we perform a detailed analysis of dark energy perturbations and we discuss their effects on current observations. This type of scenarios usually suffer from a manifest problem due to the existence of a ghost degree of freedom, and thus we review various alternative realizations of the quintom paradigm. The developments in particle physics and string theory provide potential clues indicating that a quintom scenario may be obtained from scalar systems with higher derivative terms, as well as from nonscalar systems. Additionally, we construct a quintom realization in the framework of braneworld cosmology, where the cosmic acceleration and the phantom divide crossing result from the combined effects of the field evolution on the brane and the competition between four and five dimensional gravity. Finally, we study the outsets and fates of a universe in quintom cosmology. In a scenario with null energy condition violation one may obtain a bouncing solution at early times and therefore avoid the Big Bang singularity. Furthermore, if this occurs periodically, we obtain a realization of an oscillating universe. Lastly, we comment on several open issues in quintom cosmology and their connection to future investigations.

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“…where µ and Φ 1 are integration constants. We note that the case with Φ 0 = 0 was studied in [76]; here, we generalise the aforementioned analysis by assuming that Φ 0 = 0. We also perform a more comprehensive analysis of the ensuing solutions by studying the different profiles of the coupling function, scalar field and bulk potential, which emerge as the values of the parameters of the model vary.…”

Section: The Bulk Solution and The Effective Theory On The Branementioning

confidence: 99%

Incorporating physical constraints in braneworld black-string solutions for a Minkowski brane in scalar-tensor gravity

2020

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In the framework of a general scalar-tensor theory, where the scalar field is non-minimally coupled to the five-dimensional Ricci scalar curvature, we investigate the emergence of complete brane-world solutions. By assuming a variety of forms for the coupling function, we solve the field equations in the bulk, and determine in an analytic way the form of the gravitational background and scalar field in each case. The solutions are always characterised by a regular scalar field, a finite energy-momentum tensor, and an exponentially decaying warp factor even in the absence of a negative bulk cosmological constant. The space-time on the brane is described by the Schwarzschild solution leading to either a non-homogeneous black-string solution in the bulk, when the mass parameter M is non-zero, or a regular anti-de Sitter space-time, when M = 0. We construct physically-acceptable solutions by demanding in addition a positive effective gravitational constant on our brane, a positive total energy-density for our brane and the validity of the weak energy condition in the bulk. We find that, although the theory does not allow for all three conditions to be simultaneously satisfied, a plethora of solutions emerge which satisfy the first two, and most fundamental, conditions.

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Brane models with a Ricci-coupled scalar field

Cited by 54 publications

References 27 publications

Black holes and dark energy from gravitational collapse on the brane

Black holes and dark energy from gravitational collapse on the brane

Quintom cosmology: Theoretical implications and observations

Incorporating physical constraints in braneworld black-string solutions for a Minkowski brane in scalar-tensor gravity

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