Flat rotation curves in Chern-Simons modified gravity

Konno, Kohkichi; Matsuyama, Toyoki; Asano, Yasuhiro; Tanda, Satoshi

doi:10.1103/physrevd.78.024037

Cited by 40 publications

(50 citation statements)

References 28 publications

(25 reference statements)

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“…In particular, it was found that the CS modified theory predicts an anomalous precession effect [14], which was tested [15] with LAGEOS [16]. Another constraint on the non-dynamical theory was proposed in [17], where it was considered that the CS correction could be used to explain the flat rotation curves of galaxies. However, in [18] a bound was placed on the non-dynamical model with a canonical CS scalar that is eleven orders of magnitude stronger than the Solar System one, using double binary pulsar data.…”

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confidence: 99%

Thin accretion disk signatures in dynamical Chern–Simons-modified gravity

Harkó

Kovács

Lobo

2010

Class. Quantum Grav.

104

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A promising extension of general relativity is Chern-Simons (CS) modified gravity, in which the Einstein-Hilbert action is modified by adding a parity-violating CS term, which couples to gravity via a scalar field. In this work, we consider the interesting, yet relatively unexplored, dynamical formulation of CS modified gravity, where the CS coupling field is treated as a dynamical field, endowed with its own stress-energy tensor and evolution equation. We consider the possibility of observationally testing dynamical CS modified gravity by using the accretion disk properties around slowly-rotating black holes. The energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and compared to the standard general relativistic Kerr solution. It is shown that the Kerr black hole provide a more efficient engine for the transformation of the energy of the accreting mass into radiation than their slowly-rotating counterparts in CS modified gravity. Specific signatures appear in the electromagnetic spectrum, thus leading to the possibility of directly testing CS modified gravity by using astrophysical observations of the emission spectra from accretion disks.

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confidence: 99%

Thin accretion disk signatures in dynamical Chern–Simons-modified gravity

Harkó

Kovács

Lobo

2010

Class. Quantum Grav.

104

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“…Despite these drawbacks, the Alexander-Yunes far field solution and the KMT slow rotating solution are useful for understanding the CS effects on physical observables. KMAT [33] showed that their solution remarkably explains galactic flat rotation curves without the need to invoke hypothetical dark matter. They also calculated the effect of frame dragging on spin precession, which could provide a way to observationally test CS gravity.…”

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confidence: 99%

“…In this paper, we shall consider the KMT solution [33,34] to study the effects of CS modified gravity on the phase shift in neutron interferometry using, in addition, the equations of optical-mechanical analogy for rotating sources [36]. The final formula for phase shift shows a combination of different effects.…”

Section: Introductionmentioning

confidence: 99%

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Quantum phase shift in Chern-Simons modified gravity

Nandi

Kizirgulov²,

Mikolaychuk³

et al. 2009

Phys. Rev. D

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Using a unified approach of optical-mechanical analogy in a semiclassical formula, we evaluate the effect of Chern-Simons modified gravity on the quantum phase shift of de Broglie waves in neutron interferometry. The phase shift calculated here reveals, in a single equation, a combination of effects coming from Newtonian gravity, inertial forces, Schwarzschild and Chern-Simons modified gravity. However the last two effects, though new, turn out to be too tiny to be observed, and hence only of academic interest at present. The approximations, wherever used, as well as the drawbacks of the non-dynamical approach are clearly indicated. PACS numbers(s): 95.85. Ry, 12.15.Ff, 04.50.+h

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“…To circumvent this difficulty, in [5,9], the concept of the dynamical Chern-Simons coefficient was introduced. Within this formulation, where the function θ multiplying the topological * RR term in the modified gravity action is considered as a dynamical variable, it was shown that the Kerr metric must be adequately modified to satisfy the new modified equations of motion involving dynamics of θ as well [10]. Therefore, a natural problem emerges -whether other known metrics, or, probably, other parameters of the theory must suffer any modification to solve the modified equations of motion?…”

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confidence: 99%