Presence of a fundamental acceleration scale in galaxies

McGaugh, Stacy S.; Li, Pengfei; Lelli, Federico; Schombert, James M.

doi:10.1038/s41550-018-0615-9

Cited by 39 publications

(23 citation statements)

References 117 publications

(228 reference statements)

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“…The existence of this acceleration scale has been confirmed by a wealth of observations on the scale of galaxies (e.g. [29,[91][92][93][94]). Indeed, the dynamics of disk and elliptical galaxies in the low-acceleration regime is described in the RG framework without requiring the existence of dark matter [72,74].…”

Section: The Gravitational Field Of a Spherical Source Immersed In A ...mentioning

confidence: 80%

“…In addition, in the weak-field limit, Ξ sets an acceleration scale, (2Ξ) 1/2 ∼ 10 −10 m s −2 , below which RG deviates from Newtonian gravity and appears to describe the dynamics of disk and elliptical galaxies without the aid of dark matter [72,74]. This acceleration scale is indeed present in real systems [92,93] and is comparable to the acceleration a 0 introduced in MOND [36][37][38]. Therefore, CRG provides a connection between phenomena generally attributed to dark matter and dark energy separately.…”

Section: Discussionmentioning

confidence: 91%

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Covariant Formulation of refracted gravity

Sanna¹,

Matsakos²,

Diaferio³

2021

Preprint

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We propose a covariant formulation of refracted gravity (RG), a classical theory of gravity based on the introduction of the gravitational permittivity -a monotonic function of the local mass density -in the standard Poisson equation. The gravitational permittivity mimics the dark matter phenomenology. Our covariant formulation of RG (CRG) belongs to the class of scalar-tensor theories, where the scalar field ϕ has a self-interaction potential V(ϕ) = −Ξϕ, with Ξ a normalization constant. We show that the scalar field is twice the gravitational permittivity in the weak-field limit. Far from a spherical source of density ρs(r), the transition between the Newtonian and the RG regime appears below the acceleration scale aΞ = (2Ξ − 8πGρ/ϕ) 1/2 , with ρ = ρs + ρ bg and ρ bg an isotropic and homogeneous background. In the limit 2Ξ 8πGρ/ϕ, we obtain aΞ ∼ 10 −10 m s −2 . This acceleration is comparable to the acceleration a0 originally introduced in Modified Newtonian Dynamics (MOND). From CRG, we also derive the modified Friedmann equations for an expanding, homogeneous, and isotropic universe. We find that the same scalar field that mimics dark matter also drives the accelerated expansion of the Universe. Since Ξ plays a role roughly similar to the cosmological constant Λ in the standard model and has a comparable value, CRG suggests a natural explanation of the known relation a0 ∼ Λ 1/2 . CRG thus appears to describe both the dynamics of cosmic structure and the expanding Universe with a single scalar field, and falls within the family of models that unify the two dark sectors, highlighting a possible deep connection between phenomena currently attributed to dark matter and dark energy separately.

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Section: The Gravitational Field Of a Spherical Source Immersed In A ...mentioning

confidence: 80%

Section: Discussionmentioning

confidence: 91%

Covariant Formulation of refracted gravity

Sanna¹,

Matsakos²,

Diaferio³

2021

Preprint

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“…where V f is the flat rotation velocity, M b is the total baryonic mass, and X is a factor of order unity that accounts for the cylindrical geometry of disks (McGaugh et al 2018). Fitting the data from Lelli et al (2019) in log-log space with LTS_LINEFIT (Cappellari et al 2013), we find that the best-fit slope is indistinguishable from 0.25 and the vertical intrinsic scatter is 0.02 dex along V f .…”

Section: Confirming the Constancy Of The Newtonian Gravitational Constantmentioning

confidence: 91%

“…They obtained a wide distribution of g † and concluded that a universal acceleration scale is ruled out. After substantial criticism about their methodology and interpretation of data (McGaugh et al 2018;Kroupa et al 2018;Cameron et al 2020), they presented a follow-up analysis in Marra et al (2020) in which they follow Li et al (2018) in adopting physically motivated Gaussian priors on distance, inclination, and stellar mass-to-light ratio. They persist in using a flat prior on g † , resulting in severe parameter degeneracies.…”

Section: Introductionmentioning

confidence: 99%

A cautionary tale in fitting galaxy rotation curves with Bayesian techniques

Lelli

McGaugh

et al. 2021

A&A

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The application of Bayesian techniques to astronomical data is generally non-trivial because the fitting parameters can be strongly degenerated and the formal uncertainties are themselves uncertain. An example is provided by the contradictory claims over the presence or absence of a universal acceleration scale (g†) in galaxies based on Bayesian fits to rotation curves. To illustrate this we present an analysis in which the Newtonian gravitational constant GN is allowed to vary from galaxy to galaxy when fitting rotation curves from the SPARC database, in analogy to g† in the recently debated Bayesian analyses. When imposing flat priors on GN, we obtain a wide distribution of GN which, taken at face value, would rule out GN as a universal constant with high statistical confidence. However, imposing an empirically motivated log-normal prior returns a virtually constant GN with no sacrifice in fit quality. This implies that the inference of a variable GN (or g†) is the result of the combined effect of parameter degeneracies and unavoidable uncertainties in the error model. When these effects are taken into account, the SPARC data are consistent with a constant GN (and constant g†).

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“…The numerical value is given by There is presently a controversy about the validity of MOND. The research group of S. Mc Gaugh on November 13, 2018, published an article [64] in which the MOND hypothesis with a 0 = 1.15 × 10 −10 cm/s 2 has been confirmed contradicting the article by Rodrigues published on June 18, 2018, that arrived at the opposite result. In their reply to McGaugh's article [65][66][67], they upheld their conclusions questioning the statistical approach by S. McGaugh et al…”

Section: ν +mentioning

confidence: 96%

Gravity Beyond Einstein? Part II: Fundamental Physical Principles, Number Systems, Novel Groups, Dark Energy, and Dark Matter, MOND

Hauser

Dröscher²

2019

Zeitschrift Für Naturforschung A

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This article attempts to explain the underlying physics of several recent experiments and astrophysical observations that have been mystifying the physics community for quite some time. So far, none of the advanced theories beyond the standard models of particle physics and cosmology have shown sufficient potential to resolve these mysteries. The reason for this failure may lie in the fact that these theories are based on the concept ofextra space dimensionsthat appears to be in conflict with numerous experiments, in particular with recent Large Hadron Collider data. Therefore, the novel idea of extra number systems is introduced, replacing the idea of extra space dimensions. This approach is complemented by a set of fundamental physical principles that provide the constraints and guidelines for a modified physical formulation in agreement with known experimental reality. However, such a theory requires novel physical concepts in conjunction with novel symmetry groups. These groups give rise to additional types of matter, termed hypercomplex masses (which are responsible for the extreme hypercomplex gravitational fields, see below, and are also denoted asmatter flavour), including, for instance, particles of negative mass, identified with dark matter. Furthermore, four-dimensional Minkowski spacetime, assumed to be a quaside Sitterspace$dS^{1,3}$dual spacetime,$DdS^{1,3}$, with imaginary time coordinate; that is, time is acomplex quantity. The three spatial coordinates are shared by the two spacetimes. Dark matter is assumed to reside in$DdS^{1,3}$and therefore is principally invisible. On the other hand, its gravitational interaction with ordinary matter (m≥ 0) in spacetime$dS^{1,3}$is directly perceptible. The novel group structure predicts the existence of a fourth particle family of negative masses; that is, besides the dark matter particleχof mass$m_{\chi}\approx-80.77$GeV/c2, there is the dark neutrinoνχof mass$m_{\nu_{\chi}}\approx-3.23$eV/c2. Moreover, the hypercomplex group structure of gravity ($SU(2)\times SU(2)$) postulates three gravitational bosons for cosmological fields [resulting from Einstein’s theory of general relativity (GR)], the graviton$\nu_{G_{N}}$with spin 2, the novel gravitophoton$\nu_{gp}$with spin 1 (existence of weak gravitomagnetic fields of GR), and the quintessence particleνqwith spin 0, which, when present, mediates an interaction between ordinary matter (m≥ 0) and the ubiquitous scalar field of dark energy. In addition, the existence of extreme gravity fields (hypercomplex gravity) is postulated, based on the second groupSU(2), and an interaction between electromagnetism and hypercomplex gravity is predicted, mediated by three additional hypercomplex-gravity bosons. Some long-standing problems of cosmology will be addressed; namely, the Big Bang scenario and the origin of dark energy and the nature of dark matter and their relation to the modified Newtonian dynamics hypothesis will be discussed.

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Presence of a fundamental acceleration scale in galaxies

Cited by 39 publications

References 117 publications

Covariant Formulation of refracted gravity

Covariant Formulation of refracted gravity

A cautionary tale in fitting galaxy rotation curves with Bayesian techniques

Gravity Beyond Einstein? Part II: Fundamental Physical Principles, Number Systems, Novel Groups, Dark Energy, and Dark Matter, MOND

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