Astrophysics with Weyl gravity

Deliduman, Cemsinan; Kasikci, Oguzhan; Yapişkan, Barış

doi:10.1142/s0217751x18450112

Cited by 2 publications

(3 citation statements)

References 53 publications

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“…CG was demonstrated to be renormalizable [29,33] and they solved the field equations for a static and spherically symmetric system in the Newtonian limit. They found a modified Newtonian potential which contains a term that grows linearly with distance [27,[36][37][38]. This modified potential makes it possible to fit rotation curves of a huge class of galaxies [39][40][41].…”

Section: Introductionmentioning

confidence: 99%

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Astrophysical gravitational waves in conformal gravity

2018

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We investigate the gravitational radiation from binary systems in conformal gravity (CG) and massive conformal gravity (MCG). CG might explain observed galaxy rotation curves without dark matter, and both models are of interest in the context of quantum gravity. Here we show that gravitational radiation emitted by compact binaries allows us to strongly constrain both models.We work in Weyl gauge, which fixes the rescaling invariance of the models, and derive the linearized fourth-order equation of motion for the metric, which describes massless and massive modes of propagation. In the limit of a large graviton mass, MCG reduces to general relativity (GR), whereas CG does not. Coordinates are fixed by Teyssandier gauge to show that for a conserved energymomentum tensor the gravitational radiation is due to the time-dependent quadrupole moment of a non-relativistic source and we derive the gravitational energy-momentum tensor for both models. We apply our findings to the case of close binaries on circular orbits, which have been used to indirectly infer the existence of gravitational radiation prior to the direct observation of gravitational waves.As an example, we analyze the binary system PSR J1012+5307, chosen for its small eccentricity. When fixing the graviton mass in CG such that observed galaxy rotation curves could be explained without dark matter, the gravitational radiation of a binary system is much smaller than in GR. The same holds for MCG for small masses of the graviton. Thus gravitational radiation cannot explain the orbital decay of binary systems and replace dark matter simultaneously. We also analyse MCG for large graviton masses and conclude that MCG can describe the orbital periods of compact binaries in agreement with data, as it reduces to GR in that limit.

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Section: Introductionmentioning

confidence: 99%

“…Several authors claimed that light deflection is problematic in CG, but possibly there is a way out [38,[49][50][51][52][53][54][55][56]. The work of Perlick and Xu [57] represented the major criticism on CG for a long time.…”

Section: Introductionmentioning

confidence: 99%

Astrophysical gravitational waves in conformal gravity

2018

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“…This implies that the pressure of the substance would also blow. This type of solution is absurd and hence we exclude this case [28].…”

Section: Interior Spacetime and Einstein's Field Equation In F (T ) T...mentioning

confidence: 99%

Compact star in Tolman–Kuchowicz spacetime in the background of Einstein–Gauss–Bonnet gravity

Bhar¹,

Singh²,

Tello‐Ortiz³

2019

Eur. Phys. J. C

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The present work is devoted to the study of anisotropic compact matter distributions within the framework of 5-dimensional Einstein-Gauss-Bonnet gravity. To solve the field equations, we have considered that the inner geometry is described by Tolman-Kuchowicz spacetime. The Gauss-Bonnet Lagrangian LGB is coupled to Einstein-Hilbert action through a coupling constant, namely α. When this coupling tends to zero general relativity results are recovered. We analyze the effect of this parameter on the principal salient features of the model, such as energy density, radial and tangential pressure and anisotropy factor. These effects are contrasted with the corresponding general relativity results. Besides, we have checked the incidence on important mechanism: equilibrium by means of generalized Tolman-Oppenheimer-Volkoff equation and stability through relativistic adiabatic index and Abreu's criterion. Additionally, the behaviour of the subliminal sound speed of the pressure waves in the principal direction of the configuration and the conduct of the energy-momentum tensor throughout the star are analyzed employing causality condition and energy conditions, respectively. All these subjects are supported by mean of physical, mathematical and graphical survey. The M − I and M − R graphs implies that the stiffness of the equation of state (EoS) increases with α, however less stiff than GR.PACS numbers:

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Astrophysics with Weyl gravity

Cited by 2 publications

References 53 publications

Astrophysical gravitational waves in conformal gravity

Astrophysical gravitational waves in conformal gravity

Compact star in Tolman–Kuchowicz spacetime in the background of Einstein–Gauss–Bonnet gravity

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