Turnaround radius in modified gravity

Faraoni, Valerio

doi:10.1016/j.dark.2015.11.001

Cited by 49 publications

(44 citation statements)

References 76 publications

(124 reference statements)

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“…Both high-frequency quasiperiodic oscillations and jets originating at the accretion discs can be reflected by current carrying string loops in SdS and KdS spacetimes [28,33,77,78,93]. In the spherically symmetric spacetimes, the Keplerian and toroidal disc structures can be precisely described by a pseudo-Newtonian potential of Paczynski type [79,88], which appears to be useful also in studies of the motion of interacting galaxies [56,81,82] demonstrating relation of the gravitationally bound galactic systems to the so-called static radius of the SdS or KdS spacetimes [4,5,23,24,66,67]. This idea has been confirmed by the recent study of general relativistic static polytropic spheres in spacetimes with the repulsive cosmological constant [75,85].…”

Section: Introductionmentioning

confidence: 99%

Photon motion in Kerr–de Sitter spacetimes

Charbulák

Stuchlík

2017

Eur. Phys. J. C

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We study the general motion of photons in the Kerr-de Sitter black-hole and naked singularity spacetimes. The motion is governed by the impact parameters X , related to the axial symmetry of the spacetime, and q, related to its hidden symmetry. Appropriate 'effective potentials' governing the latitudinal and radial motion are introduced and their behavior is examined by the 'Chinese boxes' technique giving regions allowed for the motion in terms of the impact parameters. Restrictions on the impact parameters X and q are established in dependence on the spacetime parameters M, , a. The motion can be of orbital type (crossing the equatorial plane, q > 0) and vortical type (tied above or below the equatorial plane, q < 0). It is shown that for negative values of q, the reality conditions imposed on the latitudinal motion yield stronger constraints on the parameter X than that following from the reality condition of the radial motion, excluding the existence of vortical motion of constant radius. The properties of the spherical photon orbits of the orbital type are determined and used along with the properties of the effective potentials as criteria of classification of the KdS spacetimes according to the properties of the motion of the photon.

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Section: Introductionmentioning

confidence: 99%

Photon motion in Kerr–de Sitter spacetimes

Charbulák

Stuchlík

2017

Eur. Phys. J. C

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“…The goal is of course to constrain the additional parameters of such theories. For example, for a McVittie space-time [38][39][40] a derivation of the turn around radius can be found in [31][32][33], by analyzing geodesics and also using the quasilocal mass function of [41,42]. In [34] a constraint on the matter-galileon coupling parameter was obtained for a cubic galileon model [43].…”

Section: Introduction and Overviewmentioning

confidence: 99%

“…Since its proposal, the maximum turn around radius as a useful cosmological observable has received considerable attention in the context of modified or alternative gravity/dark energy models [31][32][33][34][35][36][37]. The goal is of course to constrain the additional parameters of such theories.…”

Section: Introduction and Overviewmentioning

confidence: 99%

Cosmic structure sizes in generic dark energy models

Bhattacharya

Tomaras

2017

Eur. Phys. J. C

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The maximum allowable size of a spherical cosmic structure as a function of its mass is determined by the maximum turn around radius R TA,max , the distance from its center where the attraction on a radial test particle due to the spherical mass is balanced with the repulsion due to the ambient dark energy. In this work, we extend the existing results in several directions. (a) We first show that, for w = −1, the expression for R TA,max found earlier, using the cosmological perturbation theory, can be derived using a static geometry as well. (b) In the generic dark energy model with arbitrary time dependent state parameter w(t), taking into account the effect of inhomogeneities upon the dark energy as well, it is shown that the data constrain w(t = today) > −2.3. (c) We address the quintessence and the generalized Chaplygin gas models, both of which are shown to predict structure sizes consistent with observations.

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“…The relation of the maximum size determined by the turnaround radius (as opposed to the more commonly used virial radius) to the mass of a cosmic structure is a recently proposed quite reliable observable [30], which can effectively distinguish the various alternative cosmological models [31] and set constraints on their parameters [32][33][34]. We also refer our reader to [35], for a discussion on general calculation of the turn around radius in alternative gravity theories admitting McVittie solutions (e.g. [36] and references therein).…”

Section: Introductionmentioning

confidence: 99%