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Simultaneous measure of the longitudinal and transversal Doppler shift for the same galaxy. If a strong dragging is present, their SR relation is broken.
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In recent years, there has been an increase in the number of papers regarding general-relativistic explanations for the dark matter phenomena in disc galaxies. The main focus of this scientific discussion is whether a previously unexamined relativistic dragging vortex could support flat rotation curves, with various research groups taking different...
Context in source publication
Context 1
... imagine observing a disc galaxy from its Minkowskian infinity. This will be in general tilted by an angle λ with respect to our line of view, so that what we see is an ellipse (see Figure 2). Now, suppose to be able to measure simultaneously the Doppler shift on the minor and major axis of this apparent ellipse, for the same distance r from the centre of the galaxy. ...
Similar publications
A recent paper suggests that MOND would better explain the difference in the distribution of rotation curves inside versus at the outer edges of galaxies. It would be due to the External Field Effect (EFE) encounter with MOND for galaxies in a uniform external field due to surrounding systems. ΛCDM, based on General Relativity (GR), respects the (s...
Citations
... However, some authors argue that the presence of nonnegligible off-diagonal components in the global galactic metric -i.e., the presence of a strong dragging vortex surrounding disc galaxies, with no Newtonian analogue -could return important corrections on the crucial measures of disc galaxy rotation curves, even in a low-energy regime. In other words, GR would allow for disc galaxy rotation sustained for a relevant fraction by the spacetime frame-dragging, coupled to the usual centripetal attraction of the matter within the galaxy [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. ...
... Moreover, the modelling of the vertical gravity in disc galaxies is, at the very least, dubious within a model devoid of internal, effective pressure. Furthermore, the rigid rotation assumption [16] directly leads to unphysical features, e.g., the null expected red-shift with respect to the asymptotic Minkowskian observers [21,27,31] as well as unreasonably large time delays in gravitational lensed images on the equatorial plane [24]. Finally, as already pointed out in [16] and studied further in [31], the BG model presents two naked singularities along the rotation axis, outside the galactic plane, i.e., two NUT rods linked by a cosmic string. ...
... However, even if considered as only a local, thin disc model, BG does not clear the criticism about the null redshift measurements by a distant observer [27,31,33]. This is due to its unphysical rigid rotation, which we believe to ultimately disqualify the model. ...
We study the impact on the average rotational dynamics and gravitational lensing of topological structures within fully general relativistic galaxy models. These topological structures do not possess a Newtonian analogue and, therefore, represent a purely general relativistic feature which could a priori impact galactic observables. We characterise these structures both for rigidly rotating and differentially rotating solutions. By employing GAIA DR3 data, we find that such topological defects can impact the transition between the rising and flat regimes of the galaxy. Furthermore, we show that topological defects produce a noticeable increase in the deflection angle produced by Milky Way-like galaxies. Finally, we find that topological singularities can be avoided within the class of differentially rotating solutions.
... Yet attempts have been made to suggest that general relativistic effects without Newtonian analogues, when properly accounted for, could explain the astrophysical observations at the galactic level. The proposed analytical solutions for stationary, axisymmetric extended disc galaxies in general relativity [12][13][14][15][16][17][18] appear to be very far from the post-Newtonian limit. Whilst the first models of this type were undoubtedly unphysical (e.g., by assuming rigid rotation [12,13]), in recent years these models have shown vast improvement, by introducing differential rotation [14][15][16][17] and even pressure [18]. ...
... The proposed analytical solutions for stationary, axisymmetric extended disc galaxies in general relativity [12][13][14][15][16][17][18] appear to be very far from the post-Newtonian limit. Whilst the first models of this type were undoubtedly unphysical (e.g., by assuming rigid rotation [12,13]), in recent years these models have shown vast improvement, by introducing differential rotation [14][15][16][17] and even pressure [18]. However, their net disconnection with any conventional post-Newtonian limit of disc galaxy dynamics has remained. ...
... The reasoning above makes it clear that it is possible that the post-Newtonian expansion could fail, even when its separation scales naively hold, for a body that (i) it is extended enough that the curvature varies significantly within it's structure; (ii) it carries a significant amount of angular momentum. We notice that this seems exactly to be the case when full GR solutions of extended rotating bodies are considered [14,16,18]. ...
Motivated by known facts about effective field theory and non-Abelian gauge theory, we argue that the post-Newtonian approximation might fail even in the limit of weak fields and small velocities under certain conditions. Namely, the post-Newtonian approximation might break down for wide extended bodies with angular momentum, where angular momentum spans significant spacetime curvature. We construct a novel dimensionless quantity that samples this breakdown, and we evaluate it by means of existing analytical solutions of rotating extended bodies and observational data. We give estimates for galaxies and binary systems, as well as our home in the Cosmos, Laniakea. We thus propose that a novel effective field theory of general relativity is needed to account for the onset of nonlocal angular momentum effetcs, with significant consequences for gravitational physics and cosmology at large.
... Moreover, the highly nonlinear nature of general relativity gives rise to a noncommutativity of averaging and limiting procedures in spacetime [5,6]. This has fundamental consequences for the dynamics of non-pointlike sources of large spatial extent, such as disc galaxies [7][8][9][10]. ...
... The crucial ingredient of the differentially rotating models [7][8][9][10], and in particular of the exact solutions of Ref. [10], is that essential nonlinearity is retained before any low energy limit is considered. No global background is assumed. ...
... The spacetime metrics can be written in the generalized Lewis-Papapetrou-Weyl form [9,10,18], ds 2 = −c 2 e 2Φ(r,z)/c 2 (dt + A(r, z) dϕ) 2 + e −2Φ(r,z)/c 2 W (r, z) 2 dϕ 2 + e 2k(r,z)/c 2 (dr 2 + dz 2 ) , ...
A new Newtonian limit of general relativity is established for stationary axisymmetric gravitationally bound differentially rotating matter distributions with internal pressure. The self-consistent coupling of quasilocal gravitational energy and angular momentum leads to a modified Poisson equation. The coupled equations of motion of the effective fluid elements are also modified, with quasilocal angular momentum and frame-dragging leading to novel dynamics. The solutions of the full system reproduce the phenonomenology of collisionless dark matter for disc galaxies, offering an explanation for their observed rotation curves. Halos of abundant cold dark matter particles are not required.
