Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy

Ezquiaga, José María; Zumalacárregui, Miguel

doi:10.3389/fspas.2018.00044

Cited by 209 publications

(217 citation statements)

References 439 publications

(584 reference statements)

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“…The field equations set E a , E ab , E, andĒ to zero on M , while the boundary conditions are given by the vanishing of B ab , B, andB on ∂M . Furthermore, our 1/ (Λ + κ 4 V ) GB coupling allows the field equations (5)- (7) to be fully compatible with the boundary conditions (8)- (9). In particular, E ab = DB ab , and the system admits the maximally symmetric solution in vacuum…”

Section: Scalar-tensor Model With Gauss-bonnet Couplingmentioning

confidence: 90%

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Luminal propagation of gravitational waves in scalar-tensor theories: The case for torsion

et al. 2019

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Scalar-tensor gravity theories with a nonminimal Gauss-Bonnet coupling typically lead to an anomalous propagation speed for gravitational waves, and have therefore been tightly constrained by multimessenger observations such as GW170817/GRB170817A. In this paper we show that this is not a general feature of scalar-tensor theories, but rather a consequence of assuming that spacetime torsion vanishes identically. At least for the case of a nonminimal Gauss-Bonnet coupling, removing the torsionless condition restores the canonical dispersion relation and therefore the correct propagation speed for gravitational waves. To achieve this result we develop a new approach, based on the first-order formulation of gravity, to deal with perturbations on these Riemann-Cartan geometries.topological invariants, e.g., the Pontryagin or Gauss-Bonnet (GB) terms, motivated by effective field theories, string theory, and particle physics [15]. From a phenomenological viewpoint, the scalar-Pontryagin modification to GR-also known as Chern-Simons modified gravity-is an interesting extension that might explain the flat galaxy rotation curves dispensing with dark matter [16], while leaving the propagation speed of GWs unaffected [17]. This interaction generates nontrivial effects when rotation is included [18][19][20][21][22][23], providing a smoking gun in future GW detectors [24][25][26][27]. The couplings between scalar fields and the GB term, on the other hand, have been studied in different setups and several solutions that exhibit spontaneous scalarization have been reported [28][29][30][31][32][33][34][35][36][37][38][39][40][41]. Their stability, however, depends on the choice of the coupling between the scalar field and the GB term [42][43][44]. In spite of this, the theory is experimentally disadvantaged from an astrophysical viewpoint, since it develops an anomalous propagation speed for GWs [45].Scalar-tensor theories have been formulated in geometries that depart from the pseudo-Riemannian framework several times in the past. In particular, the gravitational role of Riemann-Cartan (RC) geometries, characterized by curvature and torsion, was first discussed by Cartan and Einstein themselves [46], and later on in the framework of gauge theories of gravitation [47][48][49][50]. Within its simplest formulation-the Einstein-Cartan-Sciama-Kibble (ECSK) theory-torsion is a nonpropagating field sourced only by the spin density of matter. The nonminimal coupling of scalar fields to geometry dramati-arXiv:1910.00148v3 [gr-qc]

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Section: Scalar-tensor Model With Gauss-bonnet Couplingmentioning

confidence: 90%

“…where R ab is the Lorentz curvature two-form. 7 Also called the interior product and denoted by ı ξ or ξ . For our purposes, it proves most convenient to write I ξ as [cf.…”

Section: B Lorentz-covariant Lie Derivativementioning

confidence: 99%

Luminal propagation of gravitational waves in scalar-tensor theories: The case for torsion

et al. 2019

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“…In order to avoid ghost instability, one has to require b 1 (t) > 0. The propagation effects of GWs, due to these modifications, have been analyzed explicitly in the previous works [50,51]. The first possible corrections to the tensor mode mentioned above come from terms with three derivatives.…”

Section: )mentioning

confidence: 99%

Waveform of gravitational waves in the general parity-violating gravities

et al. 2020

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As an extension of our previous work [38], in this article, we calculate of gravitational-wave (GW) waveforms, produced by the coalescence of compact binaries, in the most general parityviolating gravities, including Chern-Simons modified gravity, ghost-free scalar-tensor gravity, symmetric teleparallel equivalence of GR theory, Hořava-Lifshitz gravity and so on. With a unified description of GW in the theories of parity-violating gravity, we study the effects of velocity and amplitude birefringence on the GW waveforms. Decomposing the GWs into the circular polarization modes, the two birefringence effects exactly correspond to the modifications in phase and amplitude of GW waveforms respectively. We find that, for each circular polarization mode, the amplitude, phase and velocity of GW can be modified by both the parity-violating terms and parity-conserving terms in gravity. Therefore, in order to test the parity symmetry in gravity, we should compare the difference between two circular polarization modes, rather than measuring an individual mode. Combining two circular modes, we obtain the GW waveforms in the Fourier domain, and obtain the deviations from those in General Relativity. The GW waveforms derived in this paper are also applicable to the theories of parity-conserving gravity, which have the modified dispersion relations (e.g. massive gravity, double special relativity theory, extra-dimensional theories, etc), or/and have the modified friction terms (e.g. nonlocal gravity, gravitational theory with time-dependent Planck mass, etc).Gravitational waves (GWs) are always produced in the circumstances with extreme conditions (e.g. the strongest gravitational field, the densest celestial bodies, the earliest stage of the universe, the highest energy scale physics, etc), and have the weak interactions with other matters during the propagation [1][2][3]. Therefore, the GWs encode the cleanest information for these extreme conditions, and provides the excellent opportunity to study the physics in these extreme circumstances. As an example of the applications, GWs can be used to test the theory of gravity [4,5], which has become an important topic in the era of GW astronomy [6][7][8][9][10][11][12]. Although Einstein's General Relativity (GR) has been considered to be the most successful theory of gravity since it was proposed, it faces the difficulties in both theoretically (e.g. singularity, quantization, etc), and observationally (e.g. dark matter, dark energy, etc). Therefore, testing GR in various circumstance is an important topic since its birth [13][14][15][16][17][18].As well known, symmetry permeates nature and is fundamental to all laws of physics. Thus, one important method for the gravity examination is to test the symmetries in gravity. In our series of works, we focus on the testing of parity symmetry in gravity. Parity symmetry implies that a directional flipping to the left and right does not change the laws of physics. It is well known that nature is parity violating. Since the first discovery...

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“…The term c 2 T k 2 + µ 2 accounts for modifications of the GW phase. In general, all these functions depend on the parameters of a specific theory (e.g., see [40,41] and references therein for more details on the physical interpretation of these functions).…”

Section: Gravitational Waves In Modified Gravitymentioning

confidence: 99%

Forecasts on the speed of gravitational waves at high z

Bonilla

D’Agostino

Nunes

et al. 2020

J. Cosmol. Astropart. Phys.

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The observation of GW170817 binary neutron star (BNS) merger event has imposed strong bonds on the speed of gravitational waves (GWs) locally, inferring that the speed of GWs propagation is equal to the speed of light. Current GW detectors in operation will not be able to observe BNS merger to long cosmological distance, where possible cosmological corrections on the cosmic expansion history are expected to play an important role, specially for investigating possible deviations from general relativity. Future GW detectors designer projects will be able to detect many coalescences of BNS at high z, such as the third generation of the ground GW detector called Einstein Telescope (ET) and the space-based detector deci-hertz interferometer gravitational wave observatory (DECIGO). In this paper, we relax the condition cT /c = 1 to investigate modified GW propagation where the speed of GWs propagation is not necessarily equal to the speed of light. Also, we consider the possibility for the running of the Planck mass corrections on modified GW propagation. We parametrize both corrections in terms of an effective GW luminosity distance and we perform a forecast analysis using standard siren events from BNS mergers, within the sensitivity predicted for the ET and DECIGO. We find very strong constraints on the running of the Planck mass, namely O(10 −1 ) and O(10 −2 ) from ET and DECIGO, respectively. Possible anomalies on GW propagation are bound to |cT /c − 1| ≤ 10 −2 (10 −3 ) from ET (DECIGO). We finally discuss the consequences of our results on modified gravity phenomenology. PACS numbers: 98.80.-k, 95.36.+x, 04.50.Kd, 04.30.Nk arXiv:1910.05631v1 [gr-qc]

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Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy

Cited by 209 publications

References 439 publications

Luminal propagation of gravitational waves in scalar-tensor theories: The case for torsion

Luminal propagation of gravitational waves in scalar-tensor theories: The case for torsion

Waveform of gravitational waves in the general parity-violating gravities

Forecasts on the speed of gravitational waves at high z

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