Effects of Scalar-Tensor-Vector Gravity on relativistic jets

Armengol, Federico G. Lopez; Romero, Gustavo E.

doi:10.1007/s10509-017-3197-6

Cited by 17 publications

(16 citation statements)

References 31 publications

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“…It is natural to expect deviations from GR also in the strong field limit. MOG black holes have been widely investigated in the literature, for example see [13]- [17]. While MOG is consistent with the recently discovered gravitational wave signals [12], it has been shown in [11] that the quasinormal modes of gravitational perturbations in the ringdown phase of the merging of two MOG black holes have different frequencies compared to those of GR.…”

Section: Introductionmentioning

confidence: 81%

Linear cosmological perturbations in scalar-tensor-vector gravity

2020

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We investigate the cosmological perturbations in the context of a Scalar-Tensor-Vector theory of Gravity known as MOG in the literature. Although MOG is plagued by ghosts, it does not suffer from tachyonic instability. Therefore it can be considered as a valid theory, at least in the classical limit. In the weak field limit, MOG increases the strength of gravity, and consequently addresses some astrophysical tests, without invoking dark matter particles. Recent investigations show that MOG reproduces a viable background cosmological evolution comparable to ΛCDM. However, the matter dominated era is slightly faster in MOG compared to ΛCDM. In this paper, in order to clarify whether this evolution is compatible with observations, we study the linear matter perturbations and estimate the relevant modified gravity parameters. In contrast to some current claims in the relevant literature, we show that MOG reduces the growth rate of the perturbations. We then compare MOG to the redshift space distortion (RSD) data. We find that MOG yields a much higher value than ΛCDM for the power spectrum parameter σ 8 . Although MOG cannot yet be ruled out by RSD data alone, the low growth and high σ 8 constitute a powerful challenge to the cosmological viability of MOG.

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Section: Introductionmentioning

confidence: 81%

Linear cosmological perturbations in scalar-tensor-vector gravity

2020

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“…A similar calculation of the circular orbits of massive particles in the Kerr-MOG spacetime was performed in [52]; moreover, in [53] the authors have also studied more general trajectories of massive particles moving around this spacetime metric.…”

Section: A Geodesics Of Massive Particlesmentioning

confidence: 97%

Mass and spin of a Kerr black hole in modified gravity and a test of the Kerr black hole hypothesis

2018

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In this paper we compute the Arnowitt-Deser-Misner (ADM) mass, the angular momentum and the charge of the Kerr black hole solution in the scalar-tensor-vector gravity theory [known as the Kerr-MOG (modified-gravity) black hole configuration]; we study in detail as well several properties of this solution such as the stationary limit surface, the event horizon, and the ergosphere, and conclude that the new deformation parameter α affects the geometry of the Kerr-MOG black hole significantly in addition to the ADM mass and spin parameters. Moreover, the ADM mass and black hole event horizon definitions allow us to set a novel upper bound on the deformation parameter and to reveal the correct upper bound on the black hole spin. We further find the geodesics of motion of stars and photons around the Kerr-MOG black hole. By using them we reveal the expressions for the mass and the rotation parameter of the Kerr-MOG black hole in terms of the red-and blueshifts of photons emitted by geodesic particles, i.e., by stars. These calculations supply a new and simple method to further test the general theory of relativity in its strong field limit: If the measured redand blueshifts of photons exceed the bounds imposed by the general theory of relativity, then the black hole is not of Kerr type. It could also happen that the measurements are allowed by the Kerr-MOG metric, implying that the correct description of the dynamics of stars around a given black hole should be performed using MOG or another modified theory of gravity that correctly predicts the observations. In particular, this method can be applied to test the nature of the putative black hole hosted at the center of the Milky Way in the near future.PACS numbers:

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“…The highest value of γ observationally estimated for M87 corresponds to the spine of jet and is γ ≈ 10. 124 Thus, the upper limit imposed to κ is: 121 κ ≤ 10 2 α G N . (52) In the second run, Lopez Armengol and Romero took Moffat's weak field limit prescription κ = √ αG N , and set θ A ej = 0.…”

Section: Effects On Jetsmentioning

confidence: 99%

Astrophysical Constraints on Strong Modified Gravity

Pérez

Romero

2020

Topics on Strong Gravity

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We offer a discussion on the strong field regime predictions of two families of theories that deviate from General Relativity in different aspects: f (R)-gravity and Scalar-Tensor-Vector Gravity (STVG). We discuss astrophysical effects in models based upon both matter and vacuum solutions of such theories. In particular, we analize neutron star structure and the constraints on the parameters of the theories introduced by the latest observations. We also review black hole solutions and several astrophysical consequences of them, including accretion disks and jets. Finally, we report on the implications of the detection of various gravitational wave events for these theories.

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Effects of Scalar-Tensor-Vector Gravity on relativistic jets

Cited by 17 publications

References 31 publications

Linear cosmological perturbations in scalar-tensor-vector gravity

Linear cosmological perturbations in scalar-tensor-vector gravity

Mass and spin of a Kerr black hole in modified gravity and a test of the Kerr black hole hypothesis

Astrophysical Constraints on Strong Modified Gravity

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