A tale of analogies: a review on gravitomagnetic effects, rotating sources, observers and all that

Ruggiero, Matteo Luca; Astesiano, Davide

doi:10.1088/2399-6528/ad08cf

Cited by 6 publications

(8 citation statements)

References 255 publications

(295 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Neither [29], nor the associated series [34][35][36] diverts the attention of this article from the innovations in [21], which are especially interesting and clear. We also take note of [37,38] which appeared whilst this work was in review. 4 We adopt the following sign conventions:…”

Section: Linearised Grmentioning

confidence: 95%

Gravitomagnetism and galaxy rotation curves: a cautionary tale

Lasenby,

Hobson,

Barker

2023

Class. Quantum Grav.

View full text Add to dashboard Cite

We investigate recent claims that gravitomagnetic effects in linearised general relativity can explain flat and rising rotation curves, such as those observed in galaxies, without the need for dark matter. If one models a galaxy as an axisymmetric, stationary, rotating, non-relativistic and pressureless 'dust' of stars in the gravitoelectromagnetic (GEM) formalism, we show that gravitomagnetic effects on the circular velocity $v$ of a star are $O(10^{-6})$ smaller than the standard Newtonian (gravitoelectric) effects and thus any modification of galaxy rotation curves must be negligible. Moreover, we find that gravitomagnetic effects are $O(10^{-6})$ too small to provide the vertical support necessary to maintain dynamical equilibrium. These issues are obscured if one constructs a single equation for $v$, as considered previously. We nevertheless solve this equation for a galaxy having a Miyamoto--Nagai density profile since this allows for an exact numerical integration and an accurate analytic approximation. We show that for the values of mass, $M$, and semi-major and semi-minor axes, $a$ and $b$, typical for a dwarf galaxy, the rotation curve depends only very weakly on $M$. Moreover, for aspect ratios $a/b > 2$, the rotation curves are concave over their entire range, which does not match observations in any galaxy. Most importantly, we show that for the poloidal gravitomagnetic flux $\psi$ to provide the necessary vertical support, it must become singular at the origin and have extremely large values near to it. This originates from the unwitting, but forbidden, inclusion of free-space solutions of the Poisson-like equation that determines $\psi$. We further show that recent deliberate attempts to leverage such free-space solutions against the rotation curve problem yield no deterministic modification outside the thin disk approximation, and that, in any case, the homogeneous contributions to $\psi$ are ruled out by the boundary value problem posed by any physical axisymmetric galaxy.

show abstract

Section: Linearised Grmentioning

confidence: 95%

Gravitomagnetism and galaxy rotation curves: a cautionary tale

Lasenby,

Hobson,

Barker

2023

Class. Quantum Grav.

View full text Add to dashboard Cite

show abstract

“…which, in the weak-field and slow-motion approximation, enables to describe the motion of free test particles in terms of the action of a Lorentz-like force equation, exploiting the gravitoelectromagnetic analogy [2,12,13]. In our case the gravitomagnetic effects are related to the function χ, since g 0ϕ = r 2 χ Hγ 2 and A = A ϕ e ϕ .…”

Section: Jcap02(2024)025mentioning

confidence: 99%

“…The metric (2.10) is non time-orthogonal, because g 0i ̸ = 0: this is an expected feature, since these off-diagonal terms are generally related to the rotational features of the reference frame and to the rotation of the sources of the gravitational field [2]. In particular, from g 0i it possible to formally introduce a gravitomagnetic potential…”

Section: Jcap02(2024)025mentioning

confidence: 99%

“…To avoid misunderstandings, it is important to give the right meaning to words. Even if there are various gravitoelectromagnetic analogies that arise in GR [2], gravitomagnetic effects are generally understood as the solutions of eq. (3.8), while the gravitoelectric ones are the solutions of the corresponding equation for the gravitoelectric or Newtoninan potential.…”

Section: Jcap02(2024)025mentioning

confidence: 99%

“…Actually, also in condition of weak-gravitational field there are GR effects without Newtonian analogue: this is the case of the so-called gravitomagnetic effects [2] which, roughly speaking, are determined by mass currents. As a matter of fact, it is not true that GR effects are always (much) smaller than the corresponding Newtonian ones, since the latter at times simply do not exist; but even if they do exist, the situation is not always straightforward.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stationary rotating and axially symmetric dust systems as peculiar General Relativistic objects

Ruggiero

2024

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

We study an exact solution of Einstein's equations describing a self-gravitating system, made of dust, distributed with axial symmetry and in stationary rotation, and we prove that this type of system has no Newtonian analogue. In a low-energy limit, its existence depends on the solution of a Grad-Shafranov equation in vacuum which can be interpreted as a Laplace equation for the toroidal component of the gravitomagnetic potential; in particular, in this system the relativistic rotational effects are of the order of magnitude of Newtonian ones. We therefore argue that this exact solution should contain singularities and discuss the possible consequences of using such a system as simplified model for galactic dynamics.

show abstract

Milky Way could invalidate the hypothesis of exotic matter and favor a gravitomagnetic solution to explain dark matter

Le Corre

2024

Sci Rep

View full text Add to dashboard Cite

We demonstrate a very general mathematical and physical expression of the rotation speed at the end of the galaxy (far from the vast majority of the galaxy’s baryonic mass) obtained from General Relativity without non-baryonic matter. We show the excellent agreement with measurements obtained for the Milky Way published in a recent article which confirms a significantly faster decline in the circular velocity curve at outer galactic radii up to 30 kpc compared to the inner parts. This relation comes from Linearized General Relativity (GRL). Some papers argue that the GRL solution cannot explain dark matter (DM). We demonstrate that this conclusion is too premature because they only consider mass currents of the galaxies which is not the most general theoretical solution. And because this GRL explanation suffers from the same defects as exotic matter, only direct measurement of the Lense-Thirring effect can objectively reject this solution. Current experiments are not yet precise enough to test this solution. But meanwhile, if the relevance of this expression were confirmed for most galaxies, this would strongly challenge exotic matter to explain DM and could drastically change the point of view on the DM component. Two known physical fields (contrary to an exotic matter) which are until now neglected or rather underestimated would then explain DM. The DM mystery would then consist for theory in understanding how the values of these fields can be larger than expected and for observation in being able to measure these two fields with sufficient precision. In addition, these fields allow obtaining the TULLY-FISHER relation and the MOND theory.

show abstract

A tale of analogies: a review on gravitomagnetic effects, rotating sources, observers and all that

Cited by 6 publications

References 255 publications

Gravitomagnetism and galaxy rotation curves: a cautionary tale

Gravitomagnetism and galaxy rotation curves: a cautionary tale

Stationary rotating and axially symmetric dust systems as peculiar General Relativistic objects

Milky Way could invalidate the hypothesis of exotic matter and favor a gravitomagnetic solution to explain dark matter

Contact Info

Product

Resources

About