Galaxy rotation curves via conformal factors

Sporea, Ciprian A.; Borowiec, A.; Wojnar, Aneta

doi:10.1140/epjc/s10052-018-5792-2

Cited by 14 publications

(20 citation statements)

References 72 publications

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“…In case of scalar-tensor gravity in the Palatini approach, we decided to follow on [25] (5b) is applied, geodesics are not preserved (unless γ 3 = 0), thus leading to emergence of an unobserved "fifth force", causing particles to deviate from their standard trajectories, see e.g. [64] for application to explaining galaxy rotational curves.…”

Section: Transformation Formulaementioning

confidence: 99%

Palatini frames in scalar–tensor theories of gravity

Kozak

Borowiec

2019

Eur. Phys. J. C

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A new systematic approach extending the notion of frames to the Palatini scalartensor theories of gravity in various dimensions n > 2 is proposed. We impose frame transformation induced by the group action which includes almost-geodesic and conformal transformations. We characterize theories invariant with respect to these transformations dividing them up into solution-equivalent subclasses (group orbits). To this end, invariant characteristics have been introduced. The formalism provides new frames incorporating non-metricity that lead to re-definition of Jordan frames. The case of Palatini F (R)-gravity is considered in more detail. ContentsAppendices A. Metric scalar-tensor gravity B. Transformation groups and their consistent actions C. From F (R) to scalar-tensor gravity D. Almost-geodesic mappings References

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Section: Transformation Formulaementioning

confidence: 99%

Palatini frames in scalar–tensor theories of gravity

Kozak

Borowiec

2019

Eur. Phys. J. C

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“…Under the similar conditions as mentioned for eqn. (8), the velocity in the present case is also determined by the same relation as the eqn. (8).…”

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confidence: 93%

“…(8), the velocity in the present case is also determined by the same relation as the eqn. (8). Thus, this velocity relation actually works for all the range of velocities of massive objects.…”

mentioning

confidence: 93%

“…The eqn. (8) immediately indicates that βr has to be comparable and within an order of magnitude of λ/r to effectively raise the rotation curves above what results from the Newtonian gravity.…”

mentioning

confidence: 93%

“…More work has been done along this line following Carmeli's 1998 work [5]. There are other recent approaches to explain galaxy rotation curves using conformal gravity [6,7], Palatini formalism [8], using Grumiller's modified gravity [9] etc.…”

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confidence: 99%

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Galaxy rotation curves from external influence on Schwarzschild geometry

Bhattacharyay¹

2020

Preprint

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We introduce the postulate that the observed galaxy rotation curves indicate there exists no Minkowski limit at the scales of galaxies and beyond. It is shown here that a wide range of galaxy rotation curves can be obtained as a perturbation of the weak field limit of the Schwarzschild geometry. The theory explains why galaxy rotation curves are non Keplerian where the planetary motions are Keplerian. If the radius of a spiral galaxy is r and its Schwarzschild radius based on luminous mass is λ, the present theory predicts that r √ λr0 where r0 is the radius of the universe. The theory also derives that the ordinary matter of the universe has a mass c 2 r0/2G, where G is the gravitational constant and c is velocity of light in vacuum.

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Teleparallel gravity: from theory to cosmology

et al. 2023

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Teleparallel gravity has significantly increased in popularity in recent decades, bringing attention to Einstein’s other theory of gravity. In this Review, we give a comprehensive introduction to how teleparallel geometry is developed as a gauge theory of translations together with all the other properties of gauge field theory. We also related this form of geometry to the broader metric-affine approach to forming gravitational theories where we describe a systematic way of constructing consistent teleparallel theories that respect certain physical conditions such as local Lorentz invariance. We first use teleparallel gravity to formulate a teleparallel equivalent of general relativity which is dynamically equivalent to general relativity but which may have different behaviors for other scenarios, such as quantum gravity. After setting this foundation, we describe the plethora of modified teleparallel theories of gravity that have been proposed in the literature. We attempt to connect them together into general classes of covariant gravitational theories. Of particular interest, we highlight the recent proposal of a teleparallel analogue of Horndeski gravity which offers the possibility of reviving all of the regular Horndeski contributions. In the second part of the Review, we first survey works in teleparallel astrophysics literature where we focus on the open questions in this regime of physics. We then discuss the cosmological consequences for the various formulations of teleparallel gravity. We do this at background level by exploring works using various approaches ranging from dynamical systems to Noether symmetries, and more. Naturally, we then discuss perturbation theory, firstly by giving a concise approach in which this can be applied in teleparallel gravity theories and then apply it to a number of important theories in the literature. Finally, we examine works in observational and precision cosmology across the plethora of proposal theories. This is done using some of the latest observations and is used to tackle cosmological tensions which may be alleviated in teleparallel cosmology. We also introduce a number of recent works in the application of machine learning to gravity, we do this through deep learning and Gaussian processes, together with discussions about other approaches in the literature.

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Galaxy rotation curves via conformal factors

Cited by 14 publications

References 72 publications

Palatini frames in scalar–tensor theories of gravity

Palatini frames in scalar–tensor theories of gravity

Galaxy rotation curves from external influence on Schwarzschild geometry

Teleparallel gravity: from theory to cosmology

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