Dynamics with a Nonstandard Inertia-Acceleration Relation: An Alternative to Dark Matter in Galactic Systems

We present an analysis of 12 high-resolution galactic rotation curves from The HI Nearby Galaxy Survey (THINGS) in the context of modified Newtonian dynamics (MOND). These rotation curves were selected to be the most reliable for mass modelling, and they are the highest quality rotation curves currently available for a sample of galaxies spanning a wide range of luminosities. We fit the rotation curves with the "simple" and "standard" interpolating functions of MOND, and we find that the "simple" function yields better results. We also redetermine the value of a 0 , and find a median value very close to the one determined in previous studies, a 0 = (1.22 ± 0.33) × 10 −8 cm s −2 . Leaving the distance as a free parameter within the uncertainty of its best independently determined value leads to excellent quality fits for 75% of the sample. Among the three exceptions, two are also known to give relatively poor fits in Newtonian dynamics plus dark matter. The remaining case (NGC 3198) presents some tension between the observations and the MOND fit, which might, however, be explained by the presence of non-circular motions, by a small distance, or by a value of a 0 at the lower end of our best-fit interval, 0.9 × 10 −8 cm s −2 . The best-fit stellar M/L ratios are generally in remarkable agreement with the predictions of stellar population synthesis models. We also show that the narrow range of gravitational accelerations found to be generated by dark matter in galaxies is consistent with the narrow range of additional gravity predicted by MOND.

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“…Milgrom (1994) has shown that within the modified inertia framework, Eq. (1) was exact only for circular orbits.…”

Section: Mond and Its Interpolating Functionmentioning

confidence: 99%

THINGS about MOND

Gentile

Famaey

Blok

2011

A&A

158

219

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“…Milgrom (1994) showed that such theories always have to be time nonlocal to be Galilean invariant. As of this complication there is no full-fledged modified inertia theory developed yet (but see discussion in section 7.10 of Famaey & McGaugh 2012).…”

Section: Milgromian Dynamicsmentioning

confidence: 99%

Towards an explanation of orbits in the extreme trans-Neptunian region: The effect of Milgromian dynamics

Paučo

2017

A&A

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Context. Milgromian dynamics (MD or MOND) uniquely predicts motion in a galaxy from the distribution of its stars and gas in a remarkable agreement with observations so far. In the solar system, MD predicts the existence of some possibly non-negligible dynamical effects, which can be used to constrain the freedom in MD theories. Known extreme trans-Neptunian objects (ETNOs) have their argument of perihelion, longitude of ascending node, and inclination distributed in highly non-uniform fashion; ETNOs are bodies with perihelion distances greater than the orbit of Neptune and with semimajor axes greater than 150 au and less than ∼ 1500 au. It is as if these bodies have been systematically perturbed by some external force. Aims. We investigated a hypothesis that the puzzling orbital characteristics of ETNOs are a consequence of MD. Methods. We set up a dynamical model of the solar system incorporating the external field effect (EFE), which is anticipated to be the dominant effect of MD in the ETNOs region. We used constraints available on the strength of EFE coming from radio tracking of the Cassini spacecraft. We performed several numerical experiments, concentrating on the long-term orbital evolution of primordial (randomised) ETNOs in MD. Results. The EFE could produce distinct non-uniform distributions of the orbital elements of ETNOs that are related to the orientation of an orbit in space. If we demand that EFE is solely responsible for the detachment of Sedna and 2012 VP 113 , then these distributions are at odds with the currently observed statistics on ETNOs unless the EFE quadrupole strength parameter Q 2 has values that are unlikely (with probability < 1%) in light of the Cassini data.

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“…See Milgrom [1994] for a comprehensive review. The basic idea was conceived by Milgrom [1983a], [1983b], [1983c], as a way of understanding the flat rotation curve phenomenology of spiral galaxies without recourse to the dark matter idea.…”

Section: Overview Of Mondmentioning

confidence: 99%

Gravitation in the Fractal D = 2 Inertial Universe: New Phenomenology in Spiral Discs and a Theoretical Basis for MOND

Roscoe

2004

General Relativity and Gravitation

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A particular interpretation of Mach's Principle led us to consider if it was possible to have a globally inertial universe that was irreducibly associated with a non-trivial global matter distribution, Roscoe [2002a]. This question received a positive answer, subject to the condition that the global matter distribution is necessarily fractal, D = 2. The purpose of the present paper is to show how general gravitational processes arise in this universe. We begin by showing how classical Newtonian gravitational processes arise from point-source perturbations of this D = 2 inertial background. We are then able to use the insights gained from this initial analysis to arrive at a general theory for arbitrary material distributions. We illustrate the process by using it to model an idealized spiral galaxy. One particular subclass of solutions, corresponding to logarithmic spirals, has already been extensively tested (Roscoe [1999a(Roscoe [ ], [2002b), and shown to resolve dynamical data over large samples of optical rotation curves (ORCs) with a very high degree of statistical precision.Whilst the primary purpose of the data analysis of Roscoe [1999a] was to test the predictions of the logarithmic spiral theory, it led directly to the discovery of a major new phenomenology in spiral discs -that of discrete dynamical classes -initially reported in Roscoe [1999b] and comprehensively confirmed in Roscoe [2002b] over four large independent samples of ORCs. In this paper, we analyse the theory more comprehensively, and show how the discrete dynamical classes phenomenology has a ready explanation in terms of an algebraic consistency condition which must necessarily be satisfied.Of equal significance, we apply the theory with complete success to the detailed modelling of a sample of eight Low Surface Brightness spirals (LSBs) which, hitherto, have been succesfully modelled only by the MOND algorithm (Modified Newtonian Dynamics, Milgrom [1983a], [1983b], [1983c). The CDM models have failed comprehensively when applied to LSBs. We are able to conclude that the essence of the MOND algorithm must be contained within the presented theory.

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Dynamics with a Nonstandard Inertia-Acceleration Relation: An Alternative to Dark Matter in Galactic Systems

Cited by 212 publications

References 25 publications

THINGS about MOND

THINGS about MOND

Towards an explanation of orbits in the extreme trans-Neptunian region: The effect of Milgromian dynamics

Gravitation in the Fractal D = 2 Inertial Universe: New Phenomenology in Spiral Discs and a Theoretical Basis for MOND

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