Nonexotic matter wormholes in a trace of the energy-momentum tensor squared gravity

Moraes, P. H. R. S.; Sahoo, P. K.

doi:10.1103/physrevd.97.024007

Cited by 125 publications

(41 citation statements)

References 53 publications

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“…Furthermore, in our analysis we have obtained different numerical or relational constraints to the values of the m and n due to the existence conditions and physical features of the critical points corresponding to the second cosmological scenario. The energy-momentum squared gravity theory f (R, T 2 ) represents a recent proposal which takes into account the embeddedness of the energy-momentum squared scalar T 2 = T µν T µν and have been studied using different approaches [65,68,69,71,72]. Our study is based on the linear stability method and represents a complementary analysis of the energy-momentum squared gravity theory by investigating the phase space features and the stability properties of the critical points, associated to various cosmological epochs.…”

Section: Discussionmentioning

confidence: 99%

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Dynamical system analysis of generalized energy-momentum-squared gravity

Bahamonde

Marciu

Rudra³

2019

Phys. Rev. D

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In this work we have investigated the dynamics of a recent modification to the general theory of relativity, the energy-momentum squared gravity model f (R, T 2 ), where R represents the scalar curvature and T 2 the square of the energy-momentum tensor. By using dynamical system analysis for various types of gravity functions f (R, T 2 ), we have studied the structure of the phase space and the physical implications of the energy-momentum squared coupling. In the first case of functional where f (R, T 2 ) = f0R n (T 2 ) m , with f0 constant, we have shown that the phase space structure has a reduced complexity, with a high sensitivity to the values of the m and n parameters. Depending on the values of the m and n parameters, the model exhibits various cosmological epochs, corresponding to matter eras, solutions associated to an accelerated expansion, or decelerated periods. The second model studied corresponds to the f (R, T 2 ) = αR n + β(T 2 ) m form with α, β constant parameters.In this case it is obtained a richer phase space structure which can recover different cosmological scenarios, associated to matter eras, de-Sitter solutions, and dark energy epochs. Hence, this model represent an interesting cosmological model which can explain the current evolution of the Universe and the emergence of the accelerated expansion as a geometrical consequence.The second approach aims at modifying the geometry of spacetime, i.e. the Einstein's gravity in the general theory of relativity (GR) at large distances, specifically beyond our Solar System to produce accelerating cosmological solutions [5][6][7]. This has given rise to the concept of "modified gravity". There are numerous such theories available in literature, such as Brans-Dicke theory [8], Einstein-Cartan theory [9], Brane gravity theory [10-13], Rosen's Bimetric theory of gravity [14][15][16], Kaluza-Klein theory [17][18][19][20][21], Hořava-Lifshitz theory [22,23], etc. Extensive reviews in modified gravity theories can be found in the Refs. [24,25]. All these have their own share of merits and de-merits. Many of the theories of modified gravity aims at modifying the linear function of scalar curvature, R responsible for the Einstein tensor in the Einstein equations of GR. So it is obvious that the alterations are brought about in such a way so as to generalize the gravitational Lagrangian which takes a special form L GR = R in case of GR. An extensively studied theory in this context is the f (R) gravity where the gravitational Lagrangian L GR = R is replaced by an analytic function of R, i.e., L f (R) = f (R). Via this generalization, we can explore the non-linear effects of the scalar curvature R in the evolution of the universe by choosing a suitable function for f (R). Extensive reviews on this theory is available in the Refs. [26,27].The cosmological viability of f (R) dark energy models have been studied in [28]. In this paper the authors ruled out the f (R) theories where a power of R is dominant at large or small R. Conditions for the cosmological via...

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Section: Discussionmentioning

confidence: 99%

“…In addition to the above they have discussed simple extensions to the anisotropic cosmology. Non exotic matter wormholes are studied in the framework of EMSG in [68]. Constraints on EMSG from neutron stars was studied in [69] and compact stars in the EMSG model were studied by Nari et al in [70].…”

Section: Introductionmentioning

confidence: 99%

Dynamical system analysis of generalized energy-momentum-squared gravity

Bahamonde

Marciu

Rudra³

2019

Phys. Rev. D

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“…In this work we shall work with f (R, T) gravity theory in which the Ricci scalar R is replaced with a suitable functional form of R and trace of energy momentum tensor T [43] and therefore is a straightforward conjecture to f (R) gravity (see [44,45]). f (R, T) gravity have proved to be successful in numerous cosmological sectors such as dark matter [46] dark energy [47], massive pulsars [48,49], super-Chandrasekhar white dwarfs [50], wormholes [51][52][53][54][55][56][57][58][59][60][61], gravitational waves [62][63][64], bouncing cosmology [65,66], baryogenesis [67,68], Big-Bang nucleosynthesis [69] and in varying speed of light scenarios [70]. The article is methodized as follows: In Section II we provide a summary of f (R, T) gravity and solve the field equations assuming a bulk viscous fluid.…”

Section: Introductionmentioning

confidence: 99%

Late-time viscous cosmology in f(R, T) gravity

2021

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The article communicates an alternative route to suffice the late-time acceleration considering a bulk viscous fluid with viscosity coefficient ζ = ζ 0 + ζ 1 H + ζ 2 H 2 , where ζ 0 , ζ 1 , ζ 2 are constants in the framework of f (R, T) modified gravity. We presume the f (R, T) functional form to be f = R + 2αT where α is a constant. We then solve the field equations for the Hubble Parameter and study the cosmological dynamics of kinematic variables such as deceleration, jerk, snap and lerk parameters as a function of cosmic time. We observe the deceleration parameter to be highly sensitive to α and undergoes a signature flipping at around t ∼ 10 Gyrs for α = −0.179 which is favored by observations. The EoS parameter for our model assumes values close to −1 at t 0 = 13.7Gyrs which is in remarkable agreement with the latest Planck measurements. Next, we study the evolution of energy conditions and find that our model violate the Strong Energy Condition in order to explain the late-time cosmic acceleration. To understand the nature of dark energy mimicked by the bulk viscous baryonic fluid, we perform some geometrical diagnostics like the {r, s} and {r, q} plane. We found the model to mimic the nature of a Chaplygin gas type dark energy model at early times while a Quintessence type in distant future. Finally, we study the violation of continuity equation for our model and show that in order to explain the cosmic acceleration at the present epoch, energymomentum must violate.

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“…Nari and Roshan [16] studied physical viability and stability of compact stars in this framework. Morares and Sahoo [17] studied nonexotic matter wormholes while Akarsu [18] explored possible constraints from neutron stars in the same frame. Bahamonde et al [19] investigated the minimal and nonminimal coupling models of EMSG and observed that these models describe the current cosmic accelerated expansion.…”

Section: Introductionmentioning

confidence: 99%

Compact Stars Admitting Noether Symmetries in Energy-Momentum Squared Gravity

Sharif

Gul

2021

Advances in Astronomy

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This paper investigates the geometry of compact stellar objects through the Noether symmetry approach in the energy-momentum squared gravity. This newly developed theory overcomes the problems of big bang singularity and provides the viable cosmological consequences in the early time universe. Moreover, its implications occur in high curvature regime where the deviations of energy-momentum squared gravity from general relativity is confirmed. We consider the minimal coupling model of this modified theory and formulate symmetry generators as well as corresponding conserved quantities. We use conservation relation and apply some suitable initial conditions to evaluate the metric potentials. Finally, we explore some interesting features of the compact objects for appropriate values of the model parameters through numeric analysis. It is found that compact stellar objects in this particular framework depend on the model parameters as well as conserved quantities. We conclude that Noether symmetries generate solutions that are consistent with the astrophysical observational data and hence confirm the viability of this procedure.

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Nonexotic matter wormholes in a trace of the energy-momentum tensor squared gravity

Cited by 125 publications

References 53 publications

Dynamical system analysis of generalized energy-momentum-squared gravity

Dynamical system analysis of generalized energy-momentum-squared gravity

Late-time viscous cosmology in f(R, T) gravity

Compact Stars Admitting Noether Symmetries in Energy-Momentum Squared Gravity

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