Possibility of setting a new constraint to scalar-tensor theories

Mendes, Raissa F. P.

doi:10.1103/physrevd.91.064024

Cited by 55 publications

(70 citation statements)

References 36 publications

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“…We expect that when β > 0 scalarization will also arise in neutron stars in the massive case, as shown in the massless case by [19][20][21][22]; there is less motivation, however, to add a mass to DEF theory in the positive β branch, since, as discussed above, this branch automatically leads to a theory that passes Solar System constraints and is cosmologically viable.…”

Section: Constraintsmentioning

confidence: 99%

“…the typical branch that predicts scalarization, is exactly the one in which the field has a run-away cosmological evolution, leading to an asymptotic field value that results in grave disagreement with Solar System observations. Scalarization is still possible in the positive-β branch, for only for a restricted class of equations of state, i.e., those for which the trace of the stress energy tensor becomes negative somewhere inside the star [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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Cosmological evolution and Solar System consistency of massive scalar-tensor gravity

Alby

Yunes

2017

Phys. Rev. D

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The scalar-tensor theory of Damour and Esposito-Farèse recently gained some renewed interest because of its ability to suppress modifications to General Relativity in the weak field, while introducing large corrections in the strong field of compact objects through a process called scalarization. A large sector of this theory that allows for scalarization, however, has been shown to be in conflict with Solar System observations when accounting for the cosmological evolution of the scalar field. We here study an extension of this theory by endowing the scalar field with a mass to determine whether this allows the theory to pass Solar System constraints upon cosmological evolution for a larger sector of coupling parameter space. We show that the cosmological scalar field goes first through a quiescent phase, similar to the behavior of a massless field, but then it enters an oscillatory phase, with an amplitude (and frequency) that decays (and grows) exponentially. We further show that after the field enters the oscillatory phase, its effective energy density and pressure are approximately those of dust, as expected from previous cosmological studies. Due to these oscillations, we show that the scalar field cannot be treated as static today on astrophysical scales, and so we use time-dependent perturbation theory to compute the scalar-field-induced modifications to Solar System observables. We find that these modifications are suppressed when the mass of the scalar field and the coupling parameter of the theory are in a wide range, allowing the theory to pass Solar System constraints, while in principle possibly still allowing for scalarization.

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Section: Constraintsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cosmological evolution and Solar System consistency of massive scalar-tensor gravity

Alby

Yunes

2017

Phys. Rev. D

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“…As it is clear from the above reasoning, spontaneous scalarization can happen also for β > 0 if the nuclear equation of state is such that the pressure in the NS interior is large, p m > ρ m /3 [60][61][62][63]. If instead p m is less than ρ m /3 positive values of β will increase the mass of the scalar field inside the NS.…”

Section: B Direct Coupling Of Uldm To Matter: Violation Of the Equivmentioning

confidence: 93%

Secular effects of ultralight dark matter on binary pulsars

2020

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Dark matter (DM) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. The presence of this DM field would perturb the dynamics of celestial bodies, either because the (oscillating) DM stress tensor modifies the gravitational potentials of the galaxy, or if DM is directly coupled to the constituents of the body. We study secular variations of the orbital parameters of binary systems induced by such perturbations. Two classes of effects are identified. Effects of the first class appear if the frequency of DM oscillations is in resonance with the orbital motion; these exist for general DM couplings including the case of purely gravitational interaction. Effects of the second class arise if DM is coupled quadratically to the masses of the binary system members and do not require any resonant condition. The exquisite precision of binary pulsar timing can be used to constrain these effects. Current observations are not sensitive to oscillations in the galactic gravitational field, though a discovery of pulsars in regions of high DM density may improve the situation. For DM with direct coupling to ordinary matter, the current timing data are already competitive with other existing constraints in the range of DM masses ∼ 10 −22 − 10 −18 eV. Future observations are expected to increase the sensitivity and probe new regions of parameters.

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“…The possibility of probing a yet unconstrained region of the parameter space of STTs is based on the fact that stability properties of highly compact neutron stars may radically differ from those in GR [32]. In the scalartensor model with Gauss-Bonnet and kinetic couplings the power law dark energy solution may be described by Higgs-type potential [33].…”

Section: Introductionmentioning

confidence: 99%

Exact scalar–tensor cosmological models

Belinchón

Harkó

Mak

2017

Int. J. Mod. Phys. D

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Scalar-tensor gravitational theories are important extensions of standard general relativity, which can explain both the initial inflationary evolution, as well as the late accelerating expansion of the Universe. In the present paper we investigate the cosmological solution of a scalar-tensor gravitational theory, in which the scalar field φ couples to the geometry via an arbitrary function F (φ). The kinetic energy of the scalar field as well as its self-interaction potential V (φ) are also included in the gravitational action. By using a standard mathematical procedure, the Lie group approach, and Noether symmetry techniques, we obtain several exact solutions of the gravitational field equations describing the time evolutions of a flat Friedman-Robertson-Walker Universe in the framework of the scalar-tensor gravity. The obtained solutions can describe both accelerating and decelerating phases during the cosmological expansion of the Universe.

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Possibility of setting a new constraint to scalar-tensor theories

Cited by 55 publications

References 36 publications

Cosmological evolution and Solar System consistency of massive scalar-tensor gravity

Cosmological evolution and Solar System consistency of massive scalar-tensor gravity

Secular effects of ultralight dark matter on binary pulsars

Exact scalar–tensor cosmological models

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